The Hole‐Tunneling Heterojunction of Hematite‐Based Photoanodes Accelerates Photosynthetic Reaction
Hongwen Zhang, Pu Zhang, Jiwu Zhao, Yuan Liu, Yi Huang, Haowei Huang, Chen Yang, Yibo Zhao, Kaifeng Wu, Xianliang Fu, Shengye Jin, Yidong Hou, Zhengxin Ding, Rusheng Yuan, Maarten B. J. Roeffaers, Shuncong Zhong, Jinlin Long
Abstract
Abstract Single‐atom metal‐insulator‐semiconductor (SMIS) heterojunctions based on Sn‐doped Fe 2 O 3 nanorods (SF NRs) were designed by combining atomic deposition of an Al 2 O 3 overlayer with chemical grafting of a RuO x hole‐collector for efficient CO 2 ‐to‐syngas conversion. The RuO x ‐Al 2 O 3 ‐SF photoanode with a 3.0 nm thick Al 2 O 3 overlayer gave a >5‐fold‐enhanced IPCE value of 52.0 % under 370 nm light irradiation at 1.2 V vs. Ag/AgCl, compared to the bare SF NRs. The dielectric field mediated the charge dynamics at the Al 2 O 3 /SF NRs interface. Accumulation of long‐lived holes on the surface of the SF NRs photoabsorber aids fast tunneling transfer of hot holes to single‐atom RuO x species, accelerating the O 2 ‐evolving reaction kinetics. The maximal CO‐evolution rate of 265.3 mmol g −1 h −1 was achieved by integration of double SIMS‐3 photoanodes with a single‐atom Ni‐doped graphene CO 2 ‐reduction‐catalyst cathode; an overall quantum efficiency of 5.7 % was recorded under 450 nm light irradiation.