Oxidizing Role of Cu Cocatalysts in Unassisted Photocatalytic CO 2 Reduction Using p-GaN/Al 2 O 3 /Au/Cu Heterostructures.

Autor: Zoric MR; Stanford SUNCAT Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States.; Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States., Basera P; Stanford SUNCAT Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States., Palmer LD; Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States., Aitbekova A; Division of Engineering and Applied Science, California Institute of Technology, Pasadena, California 91125, United States., Powers-Riggs N; Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States., Lim H; Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States., Hu W; Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States., Garcia-Esparza AT; Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States.; Liquid Sunlight Alliance, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States., Sarker H; Stanford SUNCAT Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States., Abild-Pedersen F; Stanford SUNCAT Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States., Atwater HA; Division of Engineering and Applied Science, California Institute of Technology, Pasadena, California 91125, United States., Cushing SK; Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States., Bajdich M; Stanford SUNCAT Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States., Cordones AA; Stanford SUNCAT Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States.; Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States.
Jazyk: angličtina
Zdroj: ACS nano [ACS Nano] 2024 Jul 22. Date of Electronic Publication: 2024 Jul 22.
DOI: 10.1021/acsnano.4c02088
Abstrakt: Photocatalytic CO 2 reduction to CO under unassisted (unbiased) conditions was recently demonstrated using heterostructure catalysts that combine p-type GaN with plasmonic Au nanoparticles and Cu nanoparticles as cocatalysts (p-GaN/Al 2 O 3 /Au/Cu). Here, we investigate the mechanistic role of Cu in p-GaN/Al 2 O 3 /Au/Cu under unassisted photocatalytic operating conditions using Cu K-edge X-ray absorption spectroscopy and first-principles calculations. Upon exposure to gas-phase CO 2 and H 2 O vapor reaction conditions, the composition of the Cu nanoparticles is identified as a mixture of Cu I and Cu II oxide, hydroxide, and carbonate compounds without metallic Cu. These composition changes, indicating oxidative conditions, are rationalized by bulk Pourbaix thermodynamics. Under photocatalytic operating conditions with visible light excitation of the plasmonic Au nanoparticles, further oxidation of Cu I to Cu II is observed, indicating light-driven hole transfer from Au-to-Cu. This observation is supported by the calculated band alignments of the oxidized Cu compositions with plasmonic Au particles, where light-driven hole transfer from Au-to-Cu is found to be thermodynamically favored. These findings demonstrate that under unassisted (unbiased) gas-phase reaction conditions, Cu is found in carbonate-rich oxidized compositions rather than metallic Cu. These species then act as the active cocatalyst and play an oxidative rather than a reductive role in catalysis when coupled with plasmonic Au particles for light absorption, possibly opening an additional channel for water oxidation in this system.
Databáze: MEDLINE
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