Highly selective photoelectrochemical CO2 reduction by crystal phase- modulated nanocrystals without parasitic absorption

• 成果类型: Article
• 署名作者: Wang, Qingzhen; Liu, Bin; Wang, Shujie; Zhang, Peng; Wang, Tuo; Gong, Jinlong
• 署名单位: Tianjin University; Collaborative Innovation Center of Chemical Science & Engineering Tianjin; Nankai University; Haihe Laboratory of Sustainable Chemical Transformations; Tianjin University; TJU-NUS Joint Institute
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-10510
• DOI: 10.1073/pnas.2316724121
• 发表日期: 2024-01-23
• 关键词: carbon-dioxide; electrocatalytic reduction; electrochemical reduction; mechanistic insights; converting co2; catalysts; interface; efficient; surface; GROWTH

摘要

Photoelectrochemical (PEC) carbon dioxide (CO2) reduction (CO2R) holds the potential to reduce the costs of solar fuel production by integrating CO2 utilization and light harvesting within one integrated device. However, the CO2R selectivity on the photocathode is limited by the lack of catalytic active sites and competition with the hydrogen evolution reaction. On the other hand, serious parasitic light absorption occurs on the front- side-illuminated photocathode due to the poor light transmittance of CO2R cocatalyst films, resulting in extremely low photocurrent density at the CO2R equilibrium potential. This paper describes the design and fabrication of a photocathode consisting of crystal phase- modulated Ag nanocrystal cocatalysts integrated on illumination- reaction decoupled heterojunction silicon (Si) substrate for the selective and efficient conversion of CO2. Ag nanocrystals containing unconventional hexagonal close- packed phases accelerate the charge transfer process in CO2R reaction, exhibiting excellent catalytic performance. Heterojunction Si substrate decouples light absorption from the CO2R catalyst layer, preventing the parasitic light absorption. The obtained photocathode exhibits a carbon monoxide (CO) Faradaic efficiency (FE) higher than 90% in a wide potential range, with the maximum FE reaching up to 97.4% at -0.2 V vs. reversible hydrogen electrode. At the CO2/CO equilibrium potential, a CO partial photocurrent density of -2.7 mA cm-2 with a CO FE of 96.5% is achieved in 0.1 M KHCO3 electrolyte on this photocathode, surpassing the expensive benchmark Au - based PEC CO2R system.