Suppressing byproduct formation for high selective CO2 reduction over optimized Ni/TiO2 based catalysts

One of the challenges for catalytic CO2 reduction is to control product selectivity, and new findings that can modify selectivity would be transformative. Herein, two kinds of TiO2 (homemade and commercial) with the same crystal phase but different surface properties are chosen as supports to prepare Ni-based catalysts for CO2 reduction, which show distinctly different product selectivity for CO2 reduction to CH4 or CO, as well as the CO2 conversion. The catalysts based on the homemade TiO2 support are highly selective for CH4 formation, while the latter ones are about 100% selective for CO formation under the same reaction conditions. In addition, the former ones are much active (more than 3 times) than the latter ones. We found that the collaborative contribution of Ti3+ and Ni2+ species and the electronic metal-support interactions effect maybe the main driving force behind for determining the product selectivity. Methane is almost exclusively produced over the catalysts with abundant Ti3+ and Ni2+ species and greater electronic metal-support interaction, otherwise, it will give priority to CO generation. The addition of CeO2 can reduce the Ni particle size and improve the dispersion of Ni nanoparticles, as well as create more Ti3+ species, contributing to the enhancement of CO2 conversion, but shows a negligible effect on product selectivity. Furthermore, the in situ DRIFT experiments and kinetic experiments indicate that the CO route is probably involved in the CO2 reduction process over the homemade Ni-CeO2/TiO2-CO catalyst with abundant Ti3+ and Ni2+ species and a strong electronic transform effect.