TiO-Phase-Mediated Size Effect of Rh Nanoparticles on Photothermal Catalytic CO Hydrogenation.

Photothermal catalytic CO hydrogenation on TiO-based catalysts has drawn extensive attention. However, few reports have focused on the impact of particle size of the active sites by altering TiO crystal phase on the CO hydrogenation activity. Herein, we successfully regulated Rh nanoparticle size by adjusting the crystal phases of TiO at different calcination temperatures and obtained impressive photothermal catalytic CO hydrogenation performance. Notably, the anatase-phase TiO loaded with Rh nanoparticles achieved a CH production rate of 2.7 mmol h with nearly 100 % selectivity and a single-pass CO conversion rate of 69.4 %. Given the anatase-phase TiO is more favorable for the presence of surface hydroxyl groups and oxygen vacancies, which can facilitate the distribution of Rh cations, Rh nanoparticles on the anatase-phase TiO exhibited the smallest sizes. Small Rh particle size further enhanced CO adsorption and activation, leading to high photothermal CO hydrogenation performance. Furthermore, the optimized Rh nanoparticle-loaded anatase-phase TiO catalyst exhibited high structural stability and resistance to coke accumulation, maintaining stability during long-term performance tests. This work investigated the particle size effect of active sites adjusted by crystal phase of light-harvesting materials on the photothermal catalytic performance, providing guidance for the preparation of effective catalysts for CO hydrogenation to CH.