Pd-loaded Unique Urchin-structured Ga2O3 for Selective CO2 Photoreduction to CH4

Abstract

The effectiveness of photogenerated carrier separation and the restricted number of active sites result in unsatisfied CO2 photoreduction efficacy. Furthermore, the CO2 photoreduction process always shows the drawback of low product selectivity. Herein, a unique urchin-structured Ga2O3-based photocatalyst with Pd loading was designed and the relationship between the loading amount and the optimal catalytic performance was investigated. Results show Ga2O3 synthesized at 90℃ with 2% Pd loading amount (2%Pd/Ga2O3-90) exhibits an excellent yield of up to 107.48 μmol g-1 h-1 and a 99.5% selectivity of CH4. The larger specific surface area (44.7 m2/g) of Ga2O3 prepared at 90 ℃ (Ga2O3-90) can provide more active sites, simultaneously, the highly dispersed Pd nanoparticles act as both active sites for CO2 adsorption and activation and as centers for electron capture to facilitate the photogenerated carrier separate effectively. Furthermore, the in-situ DRIFTS spectra and CO adsorption isotherm of 2%Pd/Ga2O3-90 confirm the presence of key intermediates such as *CO, and *CHO, indicating CO can be captured by Pd and further protonated, thereby exhibiting 99.5% selectivity of CH4. This work provides valuable insights into the preparation of catalysts with a high specific surface area and highly selective CO2 photoreduction to CH4.