Photoreduction of CO2 on Pd-In2O3: Synergistic optimization of progressive electron transfer via amorphous/crystalline Pd and oxygen vacancies

The progressive transfer of photogenerated electrons between the catalyst components and reactants is of great significance for photocatalysis. Amorphous Pd (Pd A ) and oxygen vacancies (V O s) were simultaneously introduced in Pd-In 2 O 3 exploiting hydrogen-induced amorphization effects; 0.6 wt% Pd-In 2 O 3 exhibited a 4.5-fold increase in activity and a 3.2-fold higher selectivity toward CH 3 OH + CO (63.62 %) compared with In 2 O 3 . Multiple in situ techniques and theoretical calculations revealed that intercomponent electron transfer channels were established via various interface structures formed between Pd A or crystalline Pd (Pd C ) and In 2 O 3 ; Pd A acted as electronic pump, facilitating the transfer and separation of photogenerated electrons, resulting in their subsequent enrichment on the surface of Pd A . Simultaneously, Pd A acted as electron-donating adsorption site for H 2 O, increasing the number of electrons received by H 2 O, further inhibiting the competitive adsorption of H 2 O and CO 2 on V O sites, and promoting the hydrogen evolution reaction. Additionally, the electronic coupling between Pd C and V O s could significantly decrease the electron-donating ability of V O s, reducing the number of electrons received by CO 2 , thus effectively regulating the degree of CO 2 reduction. This study employs Pd A /Pd C and V O s to synergistic optimize the progressive transfer of photogenerated electrons, and presents a novel approach for elucidating the catalytic mechanism.