MOF‐derived Carbon‐Based Materials for Energy‐Related Applications

Liu J., Fu G., Liao Y., Zhang W., Xi X., Si F., Wang L., Zhang J., Fu X., Luo J.

The electrochemical conversion of small organic molecules to value-added chemicals and hydrogen/electricity without CO2 emissions integrates efficient energy conversions (hydrogen energy or electricity) and value-added chemical productions in one reaction system, which is essentially competitive in the carbon-neutral era. However, the activity, stability, and cost-effectiveness of electrocatalysts, as well as the safety, durability, and scalability of devices, are still challenging for their industrial applications. In addition, a lack of knowledge about relevant and detailed mechanisms restricts the further development of electrocatalysts and devices. A timely review of the electrocatalysts, devices, and mechanisms is essential to shed lights on the correct direction towards further development. In this review, the advances in the design of electrocatalysts, fabrication of devices, and understanding of reaction mechanisms are comprehensively summarized and analyzed. The major challenges are also discussed as well as the potential approaches to overcoming them. The insights for further development are provided to offer a sustainable and environmentally friendly approach to cogeneration of energy and chemicals production.

Guo X., Hao A., Li S., Li X., Wan X., Liu X., Shui J.

AbstractThe selective hydrogen oxidation reaction (HOR) electrocatalyst is crucial for enhancing the performance of proton‐exchange membrane fuel cells (PEMFCs) against degradation caused by reverse currents. In this study, a catalyst comprising platinum single atoms (Pt1) finely tuned by tungsten nanoclusters (WNC) on an accordion‐like nitrogen‐doped carbon support (ANC) is presented. The tungsten nanoclusters, derived from phosphotungstic acid, are embedded within the carbon support, while the Pt single atoms are uniformly dispersed on its surface. Experimental results and theoretical calculations reveal that the WNC effectively reduce the hydrogen adsorption strength on Pt1 to an optimal level, thereby facilitating HOR catalysis. Notably, this adjustment also weakens oxygen adsorption, rendering Pt1 less effective for catalyzing the oxygen reduction reaction. Consequently, the catalyst Pt1/WNC‐ANC exhibits high resistance to degradation from reverse currents when oxygen leaks into the anode. Meanwhile, it demonstrates an ultralow HOR overpotential with an outstanding mass activity, 13 times greater than commercial Pt/C. This work provides a highly active and selective low‐Pt HOR catalyst, paving the way for the development of cost‐effective, long‐lasting, and robust PEMFCs.

Lee C., Jung S.Y., Ryu J.H., Jeon G.S., Gaur A., Cho M.S., Ali G., Kim M., Chung K.Y., Nayak A.K., Shin S., Kwon J., Song T., Shin T.H., Han H.

AbstractDirect formic acid fuel cells (DFAFCs) stand out for portable electronic devices owing to their ease of handling, abundant fuel availability, and high theoretical open circuit potential. However, the practical application of DFAFCs is hindered by the unsatisfactory performance of electrocatalysts for the sluggish anodic formic acid oxidation reaction (FAOR). Palladium (Pd) based nanomaterials have shown promise for FAOR due to their highly selective reaction mechanism, but maintaining high electrocatalytic durability remains challenging. In this study, a novel Pd‐based electrocatalyst (UiO‐Pd‐E) is reported with exceptional durability and activity for FAOR, which can be attributed to the Pd nanoparticles encapsulated within a carbon framework where concurrent chemical alloying of Pd and Zr occurs. Further, the UiO‐Pd‐E demonstrates noteworthy multifunctionality in various electrochemical reactions including electrocatalytic ethanol oxidation reaction (EOR) and oxygen reduction reaction (ORR) in addition to the FAOR, highlighting its practical potentials.

Wang F., Wang C., Yi S.

Metal-organic frameworks (MOFs) derivatives have received extensive attentions owing to some advantages like the tunable porosity, well-exposed active sites, large surface area and high water/thermal stability. However, the conventional synthesis methods (pyrolysis in tube/muffle furnace and hydrothermal/solvothermal methods) of MOFs derivatives usually suffered from high energy consumption, long time, high risk and tedious operation steps, which hindered the further development. At present, some emerging ultrafast synthesis techniques like laser-induced heating, joule heating, microwave heating, plasma heating and magnetic-induced heating are applied to solve the above-mentioned problems. In this review, the state-of-the-art advances of various emerging synthesis methods of MOFs derivatives are introduced systematically. The relationships between physical–chemical properties of MOFs derivatives and various emerging synthesis techniques are clarified. Furthermore, the corresponding applications of MOFs derivatives prepared by the emerging techniques were introduced. Finally the challenges and perspectives of the emerging synthesis methods of MOFs derivatives are proposed. This work provides new insights of various emerging synthesis techniques for rational design and synthesis of MOFs derivatives.

Cong Y., Chen L., Liu M., Wang H., Zhang L., Zhao Q., Li C.

Constructing highly efficient ruthenium (Ru) based electrocatalysts and understanding their reaction mechanisms for hydrogen energy conversion are highly desirable, but extremely challenge. Herein, we integrate the well dispersed defective Ru nanoclusters and oxygen coordinated Ru single atoms into one electrocatalyst (RuSAO4/RuNC) toward alkaline hydrogen oxidation and evolution reactions (HOR/HER). Synergistic catalytic mechanism of dual sites has been revealed by in situ ATR SEIRAS characterization, EDTA/SCN– poisoning experiments and DFT calculations. Benefiting from the electronic redistribution between RuSAO4 and RuNC sites, the single atom RuSAO4 species can act as Lewis acid sites that display strong affinity toward interfacial water via an O down (H2O↓) conformation and subsequently promote water dissociation/formation as well as hydroxide adsorption. Meanwhile, adjacent defective Ru sites have around thermoneutral value of H adsorption free energy. RuNC works with RuSAO4 species, collaboratively reducing reaction barriers. As expected, the RuSAO4/RuNC achieves 20.3 times mass activity of commercial Pt/C for alkaline HOR at 10 mV overpotential and excellent alkaline HER activity with a low overpotential of 22 mV to deliver 10 mA cm−2, as well as considerable HER mass activity of 17.0 times compared to commercial Pt/C at 50 mV overpotential. Besides, the synergistic dual sites strategy can also be extended to prepare efficient PtSAO4/PtNC and IrSA-O4/IrNC electrocatalysts.

Zhu J., Lu X.F., Luan D., Lou X.(.

AbstractElectrochemical reduction reactions, as cathodic processes in many energy‐related devices, significantly impact the overall efficiency determined mainly by the performance of electrocatalysts. Metal–organic frameworks (MOFs) derived carbon‐supported metal materials have become one of star electrocatalysts due to their tunable structure and composition through ligand design and metal screening. However, for different electroreduction reactions, the required active metal species vary in phase component, electronic state, and catalytic center configuration, hence requiring effective customization. From this perspective, this review comprehensively analyzes the structural design principles, metal loading strategies, practical electroreduction performance, and complex catalytic mechanisms, thereby providing insights and guidance for the future rational design of such electroreduction catalysts.

Qin Y., Wang Y., Jin G., Tong X., Yang N.

AbstractCoupled electrolyzer is a desirable way to realize efficient energy conversion from electricity to chemical energy. Using coupled electrolyzers highly valuable chemicals (e.g., H2, CHxCOO−, nitrile, S, NH3, CO) can be obtained at low voltages, environmental pollutants can be alleviated, and wastewater (e.g., ammonia, urea, hydrazine) can be recycled. They are even helpful to realize the goal of carbon peaking and carbon neutrality. Compared to traditional chemical methods, small molecule‐based coupled electrolyzers are more cost‐efficient. This review summarizes state‐of‐art of coupled electrolyzers, mainly the replacement of oxygen reduction reaction with oxidation reactions of small molecules and their further coupling with cathodic reduction reactions such as hydrogen evolution reaction (HER), oxygen reduction reaction (ORR), CO2 reduction reaction (CO2RR), N2 reduction reaction (NRR), and other reduction reactions of matching small molecules. In terms of oxidation reactions of small molecules, two types of reactions are covered: sacrificial agent oxidation reaction (SAOR) and electrochemical synthesis reaction (ESR). After detailing the design principle of coupled electrolyzers and several oxidation reactions of small molecules, construction, characterization, and performance of coupled electrolyzers are systematically overviewed along with discussion and outline of current challenges and prospects of this appealing strategy.

Song J., Kumar A., Chai L., Zhao M., Sun Y., Li X., Pan J.

AbstractMetal‐air secondary batteries with ultrahigh specific energies have received vast attention and are considered new promising energy storage. The slow redox reactions between oxygen‐water molecules lead to low energy efficiency (55–71%) and limited applications. Herein, it is proposed that the MIL‐68(In)‐derived porous carbon nanotube supports the CoNiFeP heteroconjugated alloy catalyst with an overboiling point electrolyte to achieve the ultrahigh oxidation rate of water molecules. Structural characterization and density functional theory calculations reveal that the new catalyst greatly reduces the free energy of the process, and the overboiling point further accelerates the dissociation of O─H and hydrogen bonds, and the release of O2 molecules, achieving an extra‐low overpotential of 110 mV@10 mA cm−2 far lower than commercial Ir/C catalysts of 192 mV at 125 °C and state‐of‐the‐art. Furthermore, the energy efficiency of assembled rechargeable zinc‐air batteries begins to break through at 85 °C, jumps at 100 °C, and reaches ultrahigh energy efficiency of 88.1% at 125 °C with an ultralow decay rate of 0.0068% after 150 cycles far superior to those of reported metal‐air batteries. This work provides a new catalyst and electrolyte joint‐design strategy and reexamines the battery operating temperature to construct higher energy efficiency for secondary fuel cells.

Du M., Geng P., Feng W., Xu H., Li B., Pang H.

AbstractHeterostructured materials commonly consist of bifunctions due to the different ingredients. For host material in the sulfur cathode of lithium‐sulfur (Li‐S) batteries, the chemical adsorption and catalytic activity for lithium polysulfides (LiPS) are important. This work obtains a Ni5P2‐Ni nanoparticle (Ni5P2‐NiNPs) heterostructure through a confined self‐reduction method followed by an in situ phosphorization process using Al/Ni‐MOF as precursors. The Ni5P2‐Ni heterostructure not only has strong chemical adsorption, but also can effectively catalyze LiPS conversion. Furthermore, the synthetic route can keep Ni5P2‐NiNPs inside of the nanocomposites, which have structural stability, high conductivity, and efficient adsorption/catalysis in LiPS conversion. These advantages make the assembled Li–S battery deliver a reversible specific capacity of 619.7 mAh g−1 at 0.5 C after 200 cycles. The in situ ultraviolet‐visible technique proves the catalytic effect of Ni5P2‐Ni heterostructure on LiPS conversion during the discharge process.

He Q., Ning J., Chen H., Jiang Z., Wang J., Chen D., Zhao C., Liu Z., Perepichka I.F., Meng H., Huang W.

The design of binders for lithium-ion batteries is highlighted, with an emphasis on key parameters affecting device performance and failure mechanisms. These issues are discussed in detail using the example of a silicon anode and a sulfur cathode.

He Y., Liu D., Jiao J., Liu Y., He S., Zhang Y., Cheng Q., Fang Y., Mo X., Pan H., Wu R.

AbstractHard carbon (HC) has been widely regarded as the most promising anode material for sodium‐ion batteries (SIBs) due to its decent capacity and low cost. However, the poor initial Coulombic efficiency (ICE) of HC seriously hinders its practical application in SIBs. Herein, pyridinic N‐doped hard carbon polyhedra with easily accessible carbonyl groups and in situ coupled carbon nanotubes are rationally synthesized via a facile pretreated zeolitic imidazolate framework (ZIFs)‐carbonization strategy. The comprehensive ex/in situ techniques combined with theoretical calculations reveal that the synergy of pyridinic‐N and carbonyl groups promoted by the pretreatment and carbonization process would not only optimize the Na+ adsorption energy but also accelerate the desorption of Na+, significantly suppressing the irreversible capacity loss. As a result, the as‐synthesized hard carbon polyhedra as an anode can deliver an unprecedented high ICE of 98% with a large reversible capacity of 389.4 mAh g−1 at 0.03 A g−1. This work may provide an effective strategy for the structural design of HC with high ICE.

Sun C., Li Y., Li M., Sun Z., Yuan X., Jin H., Zhao Y.

Since the discovery of Rochelle salt about a century ago, ferroelectrics have been researched extensively because of their robust responses to the thermal, optical, electrical and mechanical fields. Furthermore, these researches about ferroelectric materials have been progressively extended to more diverse fields because of their unique chemical and physical properties. In this review, the most recent research progress related to the utilization of ferroelectrics in electrochemical storage systems has been summarized. First, the basic knowledge of ferroelectrics is introduced. Second, according to the order from the cathode side, the separator membrane to the anode side, the improved performance, the role of ferroelectric polarization and piezoelectric effect upon the energy storage and conversion process originated from the ferroelectric materials are revealed and discussed. Furthermore, we also offer insight into how future research may more conclusively correlate these improvements with the ferroelectricity/piezoelectricity of the ferroelectric additives. Accordingly, further progress in understanding ferroelectric physics/chemistry is expected to offer more constructive guidance about the research and development of advanced electrochemical energy storage systems.

Li Y., Ding R.

In order to cope with the global energy and environmental constraints, researchers are committed to the development of efficient and clean energy storage and conversion systems. Perovskite fluoride (ABF3), as a novel kind of electrode material, has shown excellent results in recent years in the fields of nonaqueous Li/Na/K-ion storage, aqueous supercapacitors, aqueous batteries, aqueous supercabatteries, electrocatalysis and other related areas, showing promising potential in electrochemical energy storage and conversion. This paper mainly discusses the structure of perovskite fluoride to improve its electrochemical properties by means of elemental doping, morphology control, composite construction and defects modulation, etc., and it also focuses on the electrochemical reaction mechanisms in nonaqueous/aqueous charge storage or catalytic applications, and lastly makes some development suggestions based on the current research status of perovskite fluoride.

Li Z., Zhong X., Gao L., Hu J., Peng W., Wang X., Zhou G., Xu B.

Liu Y., Zhang J., Liu Y., Zhang M., Pan Z., Cai K.

AbstractIntroducing N atoms in vanadium oxides (VOx) of aqueous Zn‐ion batteries (ZIBs) can reduce their bandgap energy and enhance their electronic conductivity, thereby promoting the diffusion of Zn2+. The close‐packed vanadium oxynitride (VON) generated often necessitates the intercalation of water molecules for restructuring, rendering it more conducive for zinc ion intercalation. However, its dense structure often causes structural strain and the formation of by‐products during this process, resulting in decreased electrochemical performance. Herein, carbon‐coated porous V2O3/VN nanosheets (p‐VON@C) are constructed by annealing vanadium metal‐organic framework in an ammonia‐contained environment. The designed p‐VON@C nanosheets are efficiently converted to low‐crystalline hydrated N‐doped VOx during subsequent activation while maintaining structural stability. This is because the V2O3/VN heterojunction and abundant oxygen vacancies in p‐VON@C alleviate the structural strain during water molecule intercalation, and accelerate the intercalation rate. Carbon coating is beneficial to prevent p‐VON@C from sliding or falling off during the activation and cycling process. Profiting from these advantages, the activated p‐VON@C cathode delivers a high specific capacity of 518 mAh g−1 at 0.2 A g−1 and maintains a capacity retention rate of 80.9% after 2000 cycles at 10 A g−1. This work provides a pathway to designing high‐quality aqueous ZIB cathodes.

Peng Z., Li H., Li J., Ao F., Cheng Y., Huang K., Yao J., Wang P., Zhao Y.

He J., Yang S., Guo Y., Mi Y., Du P.

Chai L., Song J., Jiang N., Liu X., Sun Y., Li X., Pan J.

AbstractEfficient bifunctional oxygen catalysts are essential to construct high‐performance rechargeable zinc‐air batteries (RZABs). The excessive hydrogen bond energy and the slow kinetics of H─O bond reconstruction result in low energy efficiency. Herein, an atomic confinement regulation strategy is proposed to prepare a novel catalyst CoFeDA/HC3N4 by combining CoFe DACs (dual atomic catalysts) confined on hollow carbon nitride with overboiling point hydrogen‐bonding dissociation. This new combination strategy can rationally regulate the reaction pathways and kinetics of water molecule dissociation to achieve optimized performance. The CoFeDA/HC3N4 catalyst exhibits excellent ORR and OER catalytic activity with a half‐wave potential of 0.90 V and an overpotential of 251 mV at 10 mA cm−2, fully demonstrating a stable synergistic effect of the dual coordinated Co─N2 and Fe─N2 sites. Furthermore, the assembled RZAB equipped with CoFeDA/HC3N4 achieves a super‐high‐energy efficiency (EE = 88.1%) and superb cycling stability (a decay rate of 0.0203%@20 mA cm−2) at 120 °C, revealing that over‐boiling point environment significantly enhances the dissociation rate of water and oxygen molecules during charge and discharge processes. This work provides a new design direction for the rational control of isolated DACs and a widen operating temperature window for secondary batteries.

Bi Q., Du Y., Xue Y., Zhang K., Xue J.

Choi J., Agarwal T., Park H., Jung J., Uddin A., Ahn S.M., Klein J.M., Lee A.S., Lehmann M., Fujimoto C., Park E.J., Saito T., Borup R.L., Kim Y.S.

Akkinepally B., Nadar N.R., Harisha B.S., Rao H.J., Dash T., Sharma S.C., Hussain I., Shim J.

Wang D., He T., Fan M., Li T., Qi H., Lin Z., Hu X., Su Z.

A novel carboxyl functionalized Co-MOF (–COOH) which can be used to prepare Co-MOF-g-CTS by a one-pot method with CTS was designed. (Co-MOF-g-CTS)-900 derived from Co-MOF-g-CTS exhibited the best 4-NP catalytic reduction activity.

Powell J.A., Yang Y., Zhou H.

MOF-derived carbons are a class of porous material that combine the stability of porous carbon with the functionality and versatility of MOFs. This review describes the systematic design, characterization, and application of these materials.