Metal/oxide heterostructures derived from Prussian blue analogues for efficient photocatalytic CO2 hydrogenation to hydrocarbons

Abstract

Solar-driven CO2 hydrogenation to synthesize value-added products with two or more carbons (C2+), such as paraffins and olefins, provides an alternative and potential route to solve both issues of energy shortage and environmental pollution. Nevertheless, it remains challenge to develop an efficient catalyst with high selectivity toward C2+ production. Herein, a series of NiFe-based catalysts have been successfully fabricated by thermal treatments of NiFe-Prussian blue analogues (NiFe-PBAs) in continuous air and H2 conditions. Upon H2 reduction at 250–500 °C, the obtained samples (denoted as NiFe-x) with chemical compositions of oxides, metal/oxide heterostructures and alloys, can be finely tuned. Under UV-Vis light irradiation, the NiFe-x catalysts display distinct CO2 hydrogenation performance, among which NiFe-300 catalyst affords a state-of-art CO2 conversion of 34.7 % and C2–4 selectivity of 33.6 %, respectively. Comprehensive characterizations using X-ray absorption fine structure, Mössbauer spectroscopy and steady-state photoluminescence reveal that the best-performance of NiFe-300 catalyst was composed of NiFex alloys and Fe2O3 oxides, in which the formed heterostructure can facilitate efficient charge separation and increase the surface charge density, leading to the high selectivity to C2–4 products. This study demonstrates that the Prussian blue analogues offer a new platform for the development of solar-driven catalysts for the production of value-added hydrocarbons from CO2 hydrogenation.