Catalytic Hydrogenation of CO2 by Composite Nickel Species Supported on KCl-doped Graphitic Carbon Nitride under Normal Temperature and Atmospheric Pressure

CO2 can be used as a cheap C1 feedstock to produce value-added chemical products and fuels. In this work, it was proposed for the first time that potassium chloride-doped graphitic carbon nitride-supported composite nickel species (CNS/KCl-g-C3N4) was prepared to catalyze CO2 hydrogenation with potassium borohydride (KBH4) as a hydrogen donor to produce formate at normal temperature and atmospheric pressure. The catalytic activity of CNS/KCl-g-C3N4 reached the best when the nickel loading was optimized as 15 wt%. By using CNS/KCl-g-C3N4, the hydrogen production volume and rate of KBH4 hydrolysis were reduced by 49 % and 32 %, respectively, while the formate concentration was increased by 43 %. It was speculated that the catalytic hydrogenation of CO2 was enhanced due to the chemical adsorption of CO2 on the catalyst surface by interacting with the K-N bonds and -NH2 groups, and the formation of BH4-n(OH)n- (n=0–3) with higher activity from BH4- on the Ni0 sites.