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Metal oxynitrides demonstrate promising activity for photocatalytic solar water splitting and CO2 reduction under solar irradiance aided by noble metals. Precise control of cation ratios in the oxynitrides is a necessary challenge needed to overcome for achieving effective band gap tuning. Here we report density functional theory-based calculations on intricate structure-function relationships of Zn-Ga based oxynitrides and correlate results with the experimental parameters. Crucial material property descriptors such as elemental composition, intrinsic lattice strain, and vacancy defects were exploited during the synthesis to achieve stable oxynitride photocatalysts that demonstrated CO2 conversion to CO under simulated solar spectrum, without any noble metal impregnation. The highest CO production rate surpassed that of TiO2 under the same conditions. This work inspires future research on oxynitride materials towards tailored optical properties and sustainable photocatalytic activity enabling large scale applications. 

Conversion of CO 2 in a scalable technology has the potential for enormous energy and environmental impact but remains a challenge. We present several stable, earth abundant perovskite oxide materials for the reverse water gas shift chemical looping (RWGS-CL) process as a potential solution for this CO 2 mitigation problem. This material and process combination circumvents issues plaguing other emerging technologies, viz. poor rates of CO 2 conversion, high operation temperatures, use of precious metal catalysts, or combinations thereof. Using DFT-calculated oxygen vacancy formation energy, a key descriptor for the RWGS-CL process, we have successfully predicted several earth abundant perovskite oxides with high CO 2 conversion capability. We simultaneously achieved 100% selective CO generation from CO 2 at the highest known rates (∼160 μmoles per min per gram perovskite oxide) at record low process temperatures of 450–500 °C using lanthanum and calcium based perovskite oxides. These materials are stable over several RWGS-CL cycles, enabling industrial implementation.