Slow photons for solar fuels

Jiao J., Wei Y., Zhao Y., Zhao Z., Duan A., Liu J., Pang Y., Li J., Jiang G., Wang Y.

The photocatalytic conversion of CO2 and H2O into value-added chemicals using sunlight is significant to solve energy crisis and environmental problems. In this work, a series of novel bifunctional catalysts of core-shell structured AuPd nanoparticles decorated 3DOM TiO2 (AuPd/3DOM-TiO2) w were successfully fabricated via a facile one-pot method of gas bubbling-assisted membrane reduction (GBMR). AuPd/3DOM-TiO2 catalysts show uniform 3D ordered macroporous structure, and the slow photon effect of 3DOM-TiO2 as a photonic crystal can enhance light-harvesting efficiency. AuPd nanoparticles are highly dispersed on the surface of 3DOM-TiO2 carrier. Since bimetallic AuPd nanoparticles with the relatively low Fermi level have good capacity of trapping electron, they can efficiently promote the separation of photogenerated electron-hole pairs in TiO2. The AuPd/3DOM-TiO2 catalysts exhibit excellent photocatalytic activity for CO2 reduction with H2O to CH4 under light irradiation. Among the studied catalysts, Au3Pd1/3DOM-TiO2 catalyst exhibits the highest photocatalytic activity and selectivity for CO2 reduction, e.g., its formation rate of CH4 is 18.5 μmol g−1 h−1 and its selectivity to CH4 production by CO2 reduction is 93.9%. The possible mechanism of AuPd/3DOM-TiO2 catalysts for photocatalytic CO2 reduction is also proposed, and it would guide further design and synthesis of high efficient photocatalysts for CO2 reduction with H2O.

Wu Z., Wang J., Zhou Z., Zhao G.

Highly selective oxidation of benzyl alcohol for simultaneous hydrogen production promotion with solar-driven dual photoelectrode photoelectrochemical cell.

Balamurugan M., Yun G., Ahn K., Kang S.H.

In this paper we developed a template-assisted three-dimensionally ordered BiVO4 inverse opal (IO) film by sandwich-type infiltration through self-assembled colloidal polystyrene (PS) opal beads with a diameter of 410 nm (±20 nm) for photoelectrochemical hydrogen production. Herein, the ordered BiVO4 inverse opal structure possessed a pore diameter of ∼340 nm and wall thickness of ∼20 nm, providing a large surface area. Their photoelectrochemical behavior were assessed under 1 sun illumination (100 mW/cm2 with AM 1.5 filter) in 0.5 M Na2SO4 (pH 7) which displayed a photocurrent density (Jsc) of 0.8 mA/cm2 at 1.23 V vs a normal hydrogen electrode (NHE). Low photocurrents of BiVO4 IO photoelectrodes are due to their limited photoelectrochemical ability to split water under light irradiation and their intrinsically low electronic conductivities. To overcome these problems, BiVO4 IO film was modified to deposit a nanolayer of n-type FeVO4 having a narrow band gap (Eg = 2.06 eV). The bilayered BiVO4/FeVO4 core...

Zhang H., Cheng C.

A poor electron transport property, short charge carrier diffusion lengths, and slow water oxidation kinetics severely limit the photoelectrochemical (PEC) performance of the BiVO4 photoelectrodes. To address these problems, we report the design and fabrication of a three-dimensional FTO/TiO2/BiVO4 core–shell inverse opals photoanode for PEC hydrogen production by combining atomic layer deposition and electrodeposition routes for TiO2 and BiVO4 layer deposition on F:SnO2 (FTO) inverse opal skeletons, respectively. Benefiting from the highly conductive transparent FTO invese opal networks providing fast electron pathways and TiO2/BiVO4 heterojunctions, the as-fabricated 3D FTO/TiO2/BiVO4 inverse opals photoanode delivers excellent PEC performance with a maximum photocurrent density of 4.11 mA/cm2 at 1.23 V vs a reversible hydrogen electrode in the presence of a hole scavenger in contrast to that of the counterparts FTO/TiO2 and FTO/BiVO4 inverse opals electrodes, respectively, which could be attributed to ...

Boppella R., Kochuveedu S.T., Kim H., Jeong M.J., Marques Mota F., Park J.H., Kim D.H.

In this contribution we have developed TiO2 inverse opal based photoelectrodes for photoelectrochemical (PEC) water splitting devices, in which Au nanoparticles (NPs) and reduced graphene oxide (rGO) have been strategically incorporated (TiO2@rGO@Au). The periodic hybrid nanostructure showed a photocurrent density of 1.29 mA cm-2 at 1.23 V vs RHE, uncovering a 2-fold enhancement compared to a pristine TiO2 reference. The Au NPs were confirmed to extensively broaden the absorption spectrum of TiO2 into the visible range and to reduce the onset potential of these photoelectrodes. Most importantly, TiO2@rGO@Au hybrid exhibited a 14-fold enhanced PEC efficiency under visible light and a 2.5-fold enrichment in the applied bias photon-to-current efficiency at much lower bias potential compared with pristine TiO2. Incident photon-to-electron conversion efficiency measurements highlighted a synergetic effect between Au plasmon sensitization and rGO-mediated facile charge separation/transportation, which is believed to significantly enhance the PEC activity of these nanostructures under simulated and visible light irradiation. Under the selected operating conditions the incorporation of Au NPs and rGO into TiO2 resulted in a remarkable boost in the H2 evolution rate (17.8 μmol/cm2) compared to a pristine TiO2 photoelectrode reference (7.6 μmol/cm2). In line with these results and by showing excellent stability as a photoelectrode, these materials are herin underlined to be of promising interest in the PEC water splitting reaction.

Zhang H., Zhou W., Yang Y., Cheng C.

A novel 3D WO3 /BiVO4 /cobalt phosphate composite inverse opal is designed for photoeletrochemical (PEC) water splitting, yielding a significantly improved PEC performance.

Liu J., Zhao H., Wu M., Van der Schueren B., Li Y., Deparis O., Ye J., Ozin G.A., Hasan T., Su B.

Solar light is widely recognized as one of the most valuable renewable energy sources for the future. However, the development of solar-energy technologies is severely hindered by poor energy-conversion efficiencies due to low optical-absorption coefficients and low quantum-conversion yield of current-generation materials. Huge efforts have been devoted to investigating new strategies to improve the utilization of solar energy. Different chemical and physical strategies have been used to extend the spectral range or increase the conversion efficiency of materials, leading to very promising results. However, these methods have now begun to reach their limits. What is therefore the next big concept that could efficiently be used to enhance light harvesting? Despite its discovery many years ago, with the potential for becoming a powerful tool for enhanced light harvesting, the slow-photon effect, a manifestation of light-propagation control due to photonic structures, has largely been overlooked. This review presents theoretical as well as experimental progress on this effect, revealing that the photoreactivity of materials can be dramatically enhanced by exploiting slow photons. It is predicted that successful implementation of this strategy may open a very promising avenue for a broad spectrum of light-energy-conversion technologies.

Cho S.Y., Kang S.H., Yun G., Balamurugan M., Ahn K.

Jiao J., Wei Y., Chi K., Zhao Z., Duan A., Liu J., Jiang G., Wang Y., Wang X., Han C., Zheng P.

The photonic crystal could delay the propagation of light and increase its path length through slow-light effect, which has an immense potential in improving photocatalytic conversion efficiency. In the present work, photonic crystal TiO2 (PC-TiO2) was fabricated by colloidal crystal template method, and platinum nanoparticles (Pt NPs) with different contents were deposited on the surface of PC-TiO2 carrier by the gas bubbling-assisted membrane reduction (GBMR) method. A series of Pt/PC-TiO2 photocatalysts possess well-defined inverse opals structure, and Pt NPs with uniform sizes (about 2.5 nm) homogeneously dispersed on the inner wall of carriers. The slow-light effect of photonic crystal effectively enhanced the absorption efficiency of solar irradiation. Pt deposition significantly extended the spectral response and reduced the recombination rates of photoinduced electron-hole pairs. Therefore, they exhibited superior photocatalytic activity for the reduction of CO2 with H2O. And the reaction mechanism of the CO2 photoreduction under light irradiation was proposed.

Li Z., Xin Y., Wu W., Fu B., Zhang Z.

Photoelectrochemical (PEC) water splitting is a promising technique for sustainable hydrogen generation. However, PEC performance on current semiconductors needs further improvement. Herein, a phosphorus cation doping strategy is proposed to fundamentally boost PEC performance on TiO2 nanotube photonic crystal (TiO2 NTPC) photoelectrodes in both the visible-light region and full solar-light illumination. The self-supported P-TiO2 NTPC photoelectrodes are fabricated by a facile two-step electrochemical anodization method and subsequent phosphidation treatment. The Ti4+ is partially replaced by P cations (P5+) from the crystal lattice, which narrows the band gap of TiO2 and induces charge imbalance by the formation of Ti-O-P bonds. We believe the combination of unique photonic nanostructures of TiO2 NTPCs and P cation doping strategy will open up a new opportunity for enhancing PEC performance of TiO2-based photoelectrodes.

Collins G., Armstrong E., McNulty D., O’Hanlon S., Geaney H., O’Dwyer C.

This perspective reviews recent advances in inverse opal structures, how they have been developed, studied and applied as catalysts, catalyst support materials, as electrode materials for batteries, water splitting applications, solar-to-fuel conversion and electrochromics, and finally as photonic photocatalysts and photoelectrocatalysts. Throughout, we detail some of the salient optical characteristics that underpin recent results and form the basis for light-matter interactions that span electrochemical energy conversion systems as well as photocatalytic systems. Strategies for using 2D as well as 3D structures, ordered macroporous materials such as inverse opals are summarized and recent work on plasmonic-photonic coupling in metal nanoparticle-infiltrated wide band gap inverse opals for enhanced photoelectrochemistry are provided.

Sun M., Huang S., Chen L., Li Y., Yang X., Yuan Z., Su B.

A comprehensive review of the recent progress in the applications of hierarchically structured porous materials is given.

Zheng X., Zhang L.

This review article provides a comprehensive review of recent progress in photonic nanostructures for efficient solar energy conversion.

Sun L., Yang M., Huang J., Yu D., Hong W., Chen X.

Graphitic carbon nitride (g-C3N4) has attracted tremendous attention in photocatalysis due to its extraordinary features, such as good thermal and chemical stability, metal-free composition, and easy preparation. However, the photocatalytic performance of g-C3N4 is still restricted by the limited surface area, inefficient visible light absorption, and high recombination rate of photoinduced charge carriers. Herein, a facile synthesis to produce freestanding g-C3N4 photonic crystals (PCs) by crack-free, highly ordered colloid crystals templating is reported. The PC structure succeeded from the silica opals induces bicontinuous framework, stronger optical absorption, and increase in the lifetime of photoexcited charge carriers compared to that of the bulk g-C3N4, while the chemical structure remains similar to that of the bulk g-C3N4. As such, the g-C3N4 PCs have a much higher photodegradation kinetic of methyl orange and photocatalytic hydrogen production rate which is nearly nine times the rate of bulk g-C3N4.

Zhao H., Wu M., Liu J., Deng Z., Li Y., Su B.

A ternary photocatalyst TiO 2 -Au-CdS based on three-dimensionally ordered macroporous TiO 2 (3DOM TiO 2 ) was successfully prepared to enhance the light absorption, extend the light responsive region, reduce the recombination rate of charge carriers and promote the efficiency of water splitting H 2 evolution ultimately. The obtained 3DOM TiO 2 -Au-CdS powder has a pure anatase phase of TiO 2 and greenockite structured CdS according to the XRD results and TEM analysis. Au nanoparticles (AuNPs) and CdS were evenly distributed in the 3DOM structure which enhances H 2 -generation rate under visible light by improving light harvesting and utilizing its mass transfer facilitation. As a result, the hydrogen generation rate (1.81 mmol h −1  g −1 ) using 3DOM TiO 2 -Au-CdS photocatalyst under visible light irradiation was 13-fold higher than the binary 3DOM TiO 2 -CdS reference photocatalyst. Under ultraviolet-visible light, the photogenerated electrons in TiO 2 would be transferred to recombine with the holes of CdS and under visible light, electrons would move to the conduction band (CB) of TiO 2 from CdS via AuNPs. The two different types of internal electron-transfer process in the ternary photocatalyst under ultraviolet and visible light were proposed respectively and both would efficiently reduce the recombination rate of photogenerated electrons and holes thus stimulate H 2 evolution rate. The present work demonstrated an excellent example of the synergistic effect of the light absorption enhancement by 3DOM structure, the photosensitizing and electron reservoir effect of AuNPs and the reduction of recombination rate of charge carriers by CdS to highly promote the photocatalytic activity in water splitting reaction.

Maximov Anton L., Beletskaya Irina P.

Development of the "methanol" economy may be a way to establish the new chemistry under decarbonization conditions. Methanol here is used as a raw material for production of a wide range of chemicals, conventionally obtained from oil. The key process for the "methanol" economy is the reduction of CO2, which, along with renewable energy, is the main carbon-containing resource in the low-carbon industry. This review summarizes recent data on the main approaches to methanol production from CO2: catalytic hydrogenation of CO2 with hydrogen on heterogeneous or homogeneous catalysts; electrochemical reduction of CO2 to methanol; and CO2 conversion using photocatalysis. The main advantages and disadvantages of each method, the mechanisms of CO2 conversion taking into account the features of each type of catalysis, and the main approaches to the efficient catalysts are discussed.The bibliography includes 542 references.

Jia R., Wang Y., Li A., Cheng C.

Photoelectrochemical (PEC) water splitting, using semiconductor photoelectrodes to convert solar energy into clean hydrogen energy, is a promising solution to simultaneously address the problems of traditional fossil energy shortage and...

Lv D., Hu T., Li L., Li S., Ding S., Ma F.

In order to improve the photocatalytic performance of TiO2 and expand its absorption range in the visible light region, depositing noble metals, constructing the p-n heterojunction and controlling the morphology were used to modify TiO2. First, the TiO2 photocatalyst with a three-dimensional ordered macroporous structure was prepared by vacuum impregnation combined with calcination, and then the 3DOM Ag/BiOI/TiO2 composites were successfully prepared by the in-situ deposition and photoreduction. The characterization results show that the composites present a large number of open and transparent pore structures. The pore wall is formed by stacking TiO2 nanoparticles, with BiOI and Ag nanoparticles evenly distributed on the surface of the pore wall and in the macroporous framework, which expands the specific surface area of 3DOM TiO2 and provides more active sites for the reaction. The introduction of BiOI and Ag expands the visible light response range and improves the light utilization efficiency. Furthermore, the formation of the Schottky barrier and the internal electric field formed by the p–n heterojunction effectively promotes the interfacial electron transfer and suppress the electron–hole recombination, thereby generating more active species during the photocatalytic process. The experimental results of multi-mode photocatalytic degradation of methyl orange (MO) also show that 3DOM Ag/BiOI/TiO2 photocatalyst has the best photocatalytic degradation activity. In addition, different samples were tested for hydrogen production by photolysis of water under simulated sunlight conditions, and the results show that 3DOM Ag/BiOI/TiO2 has the best hydrogen production ability of photolysis of water. The excellent performance of multi-modal photocatalytic degradation of organic pollution and high photohydrogen production activity in 3DOM Ag/BiOI/TiO2 composites is attributed to the synergistic effect between the introduction of metallic Ag, the unique 3DOM structure, and the p–n heterojunction.

Maekawa T., Huang Y., Tateishi N., Nakanishi A., Onoe T., Dong Y., Waterhouse G.I., Murai K., Moriga T.

In this study, tantalum oxynitride inverse opal (TaON IO) photonic crystals with different macropore diameters (D) were synthesized in a two-step process involving colloidal crystal templating and thermal nitridation, then applied as visible light-driven photocatalysts for hydrogen production. The TaON inverse opals showed photonic band gaps (PBGs) at visible wavelengths, with the PBG position redshifting as the diameter of the macropores increased in accordance with a modified Bragg's law expression. By aligning the electronic absorption edge of TaON (Eg ∼ 2.4 eV) with the blue edge (short-wavelength side) or red edge (long-wavelength side) of the PBGs, slow photon enhancement of photocatalytic H2 generation was realized. H2 production tests conducted in 10 vol% methanol containing H₂PtCl6 under Xe lamp irradiation (150 W) showed that the hydrogen production rate was enhanced by ∼1.3–1.4 times when the TaON absorption edge (∼510 nm) aligned with blue edge of the PBG (0.3421 mmol g−1 h−1) or the red edge of the PBG (0.3254 mmol g−1 h−1) in the inverse opals. The red edge enhancement was due to increased light absorption and charge carrier generation in TaON, whereas the blue edge effect was likely due to suppression of electron-hole pair recombination. Results demonstrate that photonic crystal engineering to exploit slow photon effects is a viable approach for boosting photocatalytic hydrogen production rates.

Jin C., Li X., Xu T., Dong J., Geng Z., Liu J., Ding C., Hu J., El ALAOUI A., Zhao Q., Liu H.

The use of zero-carbon and carbon-neutral fuels reduces emissions of conventional pollutants, but their emissions can be toxic and have various adverse effects on human health. This article reviews the possible combustion products of zero-carbon and carbon-neutral fuels, as well as their cytotoxic effects and potential health risks. At the same time, the review outlines biological models and toxicity detection methods commonly used in pollutant toxicity studies. Metals, nitrogen oxides (NOX), and ammonia (NH3) emitted from the combustion of metal fuels, hydrogen fuels, and ammonia fuels in zero-carbon fuels are harmful to human health. Exhaust emissions from carbon-neutral fuels, particularly biodiesel, and their blends with gasoline/diesel are cytotoxic, leading to severe cellular damage, such as oxidative damage, inflammatory responses, DNA damage, cell death, or apoptosis. Moreover, the normal function of the human body’s respiratory, cardiovascular, immune, digestive, urinary, and nervous systems may also be impacted by these fuel emissions according to cytotoxic research. Cytotoxicity of fuel combustion products is usually related to the fuel type, time, dose, and cell line used in the experiment. This review provides some ideas for the exhaust emission management of zero-carbon and carbon-neutral fuels and human health assessment. It also presents a theoretical and experimental basis for further research, including in vivo experiments.

Fabry D.C., Ishitani O.

Carbon dioxide (CO2) as feedstock for fuels and chemicals in an era of depleting fossil fuels poses a challenging task for future generations. Solar light as ubiquitous source of energy can be applied for the photochemical reduction of CO2 with visible light active redox photosensitizers. For the reduction of CO2 with molecular catalysts, late-transition-metal complexes, such as fac-Re(bpy)(CO)3Cl, have first been applied in the 1980s to generate carbon monoxide (CO). Different metal catalysts have been identified over the years, allowing selective formation of either CO or formic acid (HCOOH), valuable chemicals and fuel precursors. In this chapter, various molecular photocatalytic systems consisting of redox photosensitizers (PS) and various CO2-reduction catalysts (CAT) are introduced and their mechanistic highlights are summarized. The second part of the chapter lays the foundation for the construction of supramolecular photocatalysts in which the photosensitizer and catalyst units are chemically connected. In the third part, hybrid catalysts are introduced for Z-scheme applications consisting of semiconductors and the previously described supramolecular photocatalysts for CO2 reduction.

Wen F., Liu W.

This review provides the recent design and application of 3DOM materials in the field of photocatalysis, inspiring new concepts for fabricating 3DOM photocatalysts for more sustainable applications.

Tian L., Xin Q., Zhao C., Xie G., Akram M.Z., Wang W., Ma R., Jia X., Guo B., Gong J.R.

Conversion and storage of solar energy into fuels and chemicals by artificial photosynthesis has been considered as one of the promising methods to address the global energy crisis. However, it is still far from the practical applications on a large scale. Nanoarray structures that combine the advantages of nanosize and array alignment have demonstrated great potential to improve solar energy conversion efficiency, stability, and selectivity. This article provides a comprehensive review on the utilization of nanoarray structures in artificial photosynthesis of renewable fuels and high value-added chemicals. First, basic principles of solar energy conversion and superiorities of using nanoarray structures in this field are described. Recent research progress on nanoarray structures in both abiotic and abiotic-biotic hybrid systems is then outlined, highlighting contributions to light absorption, charge transport and transfer, and catalytic reactions (including kinetics and selectivity). Finally, conclusions and outlooks on future research directions of nanoarray structures for artificial photosynthesis are presented.

Yu J., Caravaca A., Guillard C., Vernoux P., Zhou L., Wang L., Lei J., Zhang J., Liu Y.

Indoor toxic volatile organic compounds (VOCs) pollution is a serious threat to people’s health and toluene is a typical representative. In this study, we developed a composite photocatalyst of carbon nitride quantum dots (CNQDs) in situ-doped TiO2 inverse opal TiO2 IO for efficient degradation of toluene. The catalyst was fabricated using a sol-gel method with colloidal photonic crystals as the template. The as-prepared catalyst exhibited excellent photocatalytic performance for degradation of toluene. After 6 h of simulated sunlight irradiation, 93% of toluene can be converted into non-toxic products CO2 and H2O, while only 37% of toluene is degraded over commercial P25 in the same condition. This greatly enhanced photocatalytic activity results from two aspects: (i) the inverse opal structure enhances the light harvesting while providing adequate surface area for effective oxidation reactions; (ii) the incorporation of CNQDs in the framework of TiO2 increases visible light absorption and promotes the separation of photo-generated charges. Collectively, highly efficient photocatalytic degradation of toluene has been achieved. In addition, it can be expanded to efficient degradation of organic pollutants in liquid phase such as phenol and Rhodamine B. This study provides a green, energy saving solution for indoor toxic VOCs removal as well as for the treatment of organic wastewater.

Chen Y., Wang Y., Fang J., Dai B., Kou J., Lu C., Zhao Y.

Owing to its photonic band gap (PBG) and slow light effects, aniline black (AB)-poly(vinylidene fluoride) (PVDF) inverse opal (IO) photonic crystal (PC) was constructed to promote the utility of light and realize photothermal synergetic catalysis. As a highly efficient reaction platform with the capability of restricting heat, a microreactor was introduced to further amplify the photothermal effects of near infrared (NIR) radiation. The photocatalytic efficiency of ZnO/0.5AB-PVDF IO (Z0.5A) increases 1.63-fold compared to that of pure ZnO film under a full solar spectrum, indicating the effectiveness of synergetic promotion by slow light and photothermal effects. Moreover, a 5.85-fold increase is achieved by combining Z0.5A with a microreactor compared to the film in a beaker. The photon localization effect of PVDF IO was further exemplified by finite-difference time-domain (FDTD) calculations. In conclusion, photonic crystal-microreactor enhanced photothermal catalysis has immense potential for alleviating the deteriorating water environment. ZnO/PVDF inverse opal film was prepared to reach photothermal synergetic catalysis in the microreactor. By utilizing photon localization effect and slow light effect, the photocatalytic performance was greatly enhanced.

Wang Y., Peng C., Jiang T., Zhang J., Jiang Z., Li X.

We report defect-engineered 3DOM WO3 photonic crystals featuring abundant oxygen vacancies, excellent charge transport properties and remarkable photocatalytic performance.

Chen Y., Fang J., Dai B., Kou J., Lu C., Xu Z.

To utilize the full solar spectrum, photonic crystal (PC) films were constructed along with CdS and Graphene Oxide (GO) nanosheets to realize photothermal synergetic catalysis. The photonic band gap (PBG) effect of PC films could enhance the absorption of near-infrared light by GO. A microreactor was introduced as the platform for photocatalysis owing to its fast mass transfer and preeminent heat-localization effect. Tetracycline, as an antibiotic widely existed in waste water, was chosen as the degradation goal of photocatalysis tests. Compared with the pure CdS film, the CdS/GO/polystyrene PC film gains a 18.3 °C temperature rise and a 57.8% photocatalytic performance promotion, indicating the effectiveness of photothermal catalysis. Moreover, the CGPC film sealed in the microreactor exhibits a 33.0 °C temperature increase and a 4.5-fold photocatalytic efficiency grow against a same film in the bulk reactor, corroborating the great mass transfer and the preeminent heat-localization effect of the microreactor. Temperature distributions in the microreactor and the bulk reactor were simulated by computational simulations to corroborate aforementioned conclusions. In conclusion, photonic crystal and microreactor enhanced photothermal catalysis provides a feasible method for water treatment.

Zhou H., Xiao C., Yang Z., Du Y.

Artificial photosynthesis is an effective way to convert solar energy into fuels, which is of great significance to energy production and reduction of atmospheric CO2 content. In recent years, 3D structured artificial photosynthetic system has made great progress as an effective design strategy. This review first highlights several typical mechanisms for improved artificial photosynthesis with 3D structures: improved light harvesting, mass transfer and charge separation. Then, we summarize typical examples of 3D structured artificial photosynthetic systems, including bioinspired structures, photonic crystals (PC), designed photonic structures (PC coupling structure, plasmon resonance structure, optical resonance structure, metamaterials), 3D-printed systems, nanowire integrated systems and hierarchical 3D structures. Finally, we discuss the problems and challenges to the application and development of 3D artificial photosynthetic system and the possible trends of future development. We hope this review can inspire more progress in the field of artificial photosynthesis.

Chen C., Wang X., Dong Z., Chen G., Zhao X., Zhu Z., Shih W., Zhu Y.

Aimed at manipulating the propagation of light and functional applications such as enhanced sensing and catalysis through intensifying light harvesting, colloidal photonic crystal (CPC) materials have attracted much research interests because of its excellent properties and potential functional applications in optical, electrical, thermal, and magnetic aspects. CPC is a dimensionally periodic dielectric structure that exhibits a photonic band-gap (PBG). The theory of CPC has been put forth for 30 years, and many achievements have been made based on theoretical and experimental research. CPC materials inhibit photons from propagating for a certain band of frequencies corresponding to the fabricated PBG. We review the characteristics of smart polymeric CPCs based on our research, including the preparation methods as well as its developmental status in sensors and catalysis in recent years. The future research focus and developmental direction are also presented.

Zhang C., Zhao P., Liu S., Yu K.

Three-dimensionally ordered macroporous (3DOM) perovskite materials have attracted the interest from researchers worldwide due to their unique macroporous structure, flexible composition, tailorable physicochemical property, high stability and biocompatibility. In particular, they were widely used in environmental field, such as photocatalysis, catalytic combustion, catalytic oxidation and sensors. In this review, the recent progresses in the synthesis of 3DOM perovskite materials and their environmental applications are summarized. The advantages and the promoting mechanisms of 3DOM perovskite materials for different applications are discussed in detail. Subsequently, the challenges and perspectives on the topic are proposed. The applications of three-dimensionally ordered macroporous perovskite materials in environmental fields are summarized, including photocatalysis, soot combustion, oxidation of volatile organic compounds, carbon dioxide methanation and sensors for gas or liquid. The materials present a good performance owing to the properties, such as slow photon effect, strong mass transfer ability, high surface area and adjustable composition.