Efficient CO2 photoreduction enabled by the one-dimensional (1D) porous structured NiTiO3 nanorods

Abstract

In this study, porous, and hollow nanorods of NiTiO3 (NiTiO3 NRs-p: 2–3 μm in length and 400 nm in diameter) are successfully prepared using an ethylene glycol-mediated approach at room temperature (25 °C), followed by calcination at 700 °C in air environment. Their rough surfaces and accumulated holes are advantageous for adsorption and subsequent photoreduction of carbon dioxide (CO2) under UV–vis irradiation. The NiTiO3 NRs-p exhibit superior performance in terms of photoconversion of CO2 (purity 99.999 %, 100 mL/min) into gaseous CO (57.833 μmolg−1 h−1) and CH4 (24.33 μmolg−1 h−1) with an overall CO2 selectivity (SCO2) of 89 %. In contrast, the solid NiTiO3 nanorods (NiTiO3 NRs) exhibit moderate performance in CO2 reduction, producing CO (30.33 μmolg−1 h−1) and CH4 (11.50 μmolg−1 h−1) with a CO2 selectivity of SCO2 = 60 %. NiTiO3 NRs-p exhibits superior photocatalytic activity against CO2 over other NiTiO3 morphologies with similar physical and chemical properties (such as nanoparticles (NPs) and nanofibers (NFs). This enhancement in photocatalytic activity can be attributed to the porous texture and hollow rod-like structure of NiTiO3 NRs-p, which provides a larger number of active sites to promote rapid mass transport. This unique one-dimensional (1D) structure also facilitates the separation of photogenerated electron-hole pairs, as demonstrated experimentally. This study opens a new room for a simple and facile routes for the photocatalytic conversion of CO2 into solar fuels.