Carbon- and Nitrogen-Doped XTiO3 (X = Ba and Ca) Titanates for Efficient CO2 Photoreduction Under Solar Light

In recent decades, photocatalysis has received huge attention as a way to address the main environmental challenges affecting planet Earth. Among these, the control of CO2 emission and its concentration in the atmosphere, as one of the greenhouse gases causing global warming, is of primary importance. This study focuses on the hydrothermal preparation of doped Ba and Ca-based titanates as efficient photocatalytic materials for CO2 photoreduction under solar light. The materials were characterized by SEM-EDX, XPS, FT-IR ATR, DRS, CHNS, XRD, and N2 physisorption analyses, and tested for gas-phase methane production from the target reaction. According to the results, the visible light harvesting properties were significantly improved with C and N doping, where glucose and a bio-based chitosan acted as the C and C+N sources, respectively. In particular, C-Ba-based titanate (CBaT) indicated the highest CH4 productivity, 2.3 µmol/gcat, against zero activity of the corresponding bare titanate structure, BaT. The larger surface area and pore volume, as well as its narrower band gap, are suggested as the major reasons for the promising performance of CBaT. This work provides new insights for the facile fabrication of efficient photoactive perovskite materials with the aim of CO2-to-CH4 photoreduction under solar light.