Enhanced Photocatalytic CO2 Reduction and Water Splitting Over a Boron-Rich Alloy Boron Suboxide (B6O) via Cr or Co Doping

Abstract Boron-rich alloy boron suboxide (B 6 O) as a novel metal-free photocatalyst was recently explored for photocatalytic CO 2 reduction and water splitting. However, to broaden the potential applications of B 6 O in the field, further improving its activity and understanding its fundamental chemical properties are essential. Herein, transition metal doping (Cr or Co) is designed to engineer the band structure of B 6 O via a solid state reaction. The valence band edge of Cr or Co doped B 6 O is proposed to be more positive than that of pristine B 6 O while the original conduction band of B 6 O is not much influenced by doping, contributing to the better light harvesting ability and lower charge recombination rate of doped B 6 O. The photocatalytic and photoelectrochemical (PEC) performances of doped B 6 O were therefore remarkably enhanced. The apparent quantum yields (AQY) of 20 wt% Cr or Co doped B 6 O are much higher than that of pristine B 6 O. In addition, the 20 wt% Cr doped B 6 O exhibits the best electrical conductivity and photocatalytic performance compared with the Co doped B 6 O and pristine B 6 O. The present work demonstrates a facile and effective strategy to engineer the band structure and reduce the charge migration resistance of B 6 O. Graphic Abstract