Decoupling Strategy for Enhanced Syngas Generation from Photoelectrochemical CO2 Reduction

• Published in: iScience 2020-08, Vol.23 (8), p.101390-101390, Article 101390
• Main Authors: Chu, Sheng, Ou, Pengfei, Rashid, Roksana Tonny, Ghamari, Pegah, Wang, Renjie, Tran, Hong Nhung, Zhao, Songrui, Zhang, Huiyan, Song, Jun, Mi, Zetian
• Format: Article
• Language: English
• Subjects: Catalysis; Electrochemical Energy Conversion; Nanomaterials
• ISSN: 2589-0042; 2589-0042
• DOI: 10.1016/j.isci.2020.101390

Photoelectrochemical CO2 reduction into syngas (a mixture of CO and H2) provides a promising route to mitigate greenhouse gas emissions and store intermittent solar energy into value-added chemicals. Design of photoelectrode with high energy conversion efficiency and controllable syngas composition is of central importance but remains challenging. Herein, we report a decoupling strategy using dual cocatalysts to tackle the challenge based on joint computational and experimental investigations. Density functional theory calculations indicate the optimization of syngas generation using a combination of fundamentally distinctive catalytic sites. Experimentally, by integrating spatially separated dual cocatalysts of a CO-generating catalyst and a H2-generating catalyst with GaN nanowires on planar Si photocathode, we report a record high applied bias photon-to-current efficiency of 1.88% and controllable syngas products with tunable CO/H2 ratios (0–10) under one-sun illumination. Moreover, unassisted solar CO2 reduction with a solar-to-syngas efficiency of 0.63% is demonstrated in a tandem photoelectrochemical cell. [Display omitted] •Combined experimental and theoretical investigations were performed•A record high applied bias photon-to-current efficiency of 1.88% was achieved•The CO/H2 ratio in the syngas product can be controllably tuned in a wide range•Unassisted syngas generation was proved in a tandem photoelectrochemical cell Catalysis; Electrochemical Energy Conversion; Nanomaterials