Palladium-modified cuprous(i) oxide with {100} facets for photocatalytic CO reduction.

Using metal as a photohole capturer can promote the photoelectron of p-type copper(i) oxide (CuO) substrate for efficient carbon dioxide reduction. However, palladium-decorated CuO (CuO-Pd) is seldom reported due to their mismatching band arrangement. Herein, we have successfully established a matched band alignment between Pd nanoparticles and CuO with exposed {100} facets (100CuO). The high work function of 100CuO originating from T symmetry vibration facilitates the photohole transferring to Pd nanoparticles, which leads to a three-fold increase in the photocatalytic generation of carbon monoxide (100CuO-0.1Pd, 0.13 μmol g h) than that with pristine 100CuO (0.04 μmol g h). Besides, the incorporation of Pd can relieve the photocorrosion of 100CuO, thus promoting its photocatalytic stability. As a contrast, 111CuO (CuO exposed to {111} facets) with low-work function was also synthesized and no charge migration was observed between 111CuO and Pd species, which verified the important role of the crystal surface regulation. All experimental phenomena were certified by the crystal surface analysis and energy band structure construction. Moreover, CO adsorption capacity tests indicated that the incorporation of Pd is beneficial for the capture of CO molecules. We hope that this work to some extent will enrich the subject of photocatalytic CO reduction.