Decoupling Strategy for Enhanced Syngas Generation from Photoelectrochemical CO 2 Reduction

• Published in: iScience 2020-08, Vol.23 (8), p.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
• ISSN: 2589-0042

Photoelectrochemical CO reduction into syngas (a mixture of CO and H ) 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 H -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/H ratios (0-10) under one-sun illumination. Moreover, unassisted solar CO reduction with a solar-to-syngas efficiency of 0.63% is demonstrated in a tandem photoelectrochemical cell.