CoSe2 modified Se-decorated CdS nanowire Schottky heterojunctions for highly efficient photocatalytic hydrogen evolution.

• CoSe 2 /CdS 0.95 Se 0.05 Schottky heterojunction were fabricated via simple method. • Se-doping can lower the work function of CdS NWs, availing the electrons escaping. • The highest HER rate of CoSe 2 /CdS 0.95 Se 0.05 is ~66 times higher than that of CdS NWs. • CoSe 2 can efficiently boost the separation and migration of charge carriers. Novel CoSe 2 nanobelts/Se-decorated CdS nanowires heterojunctions were successfully constructed via combining strategies of Se-doping and in situ loading of CoSe 2 nanobelts. Under visible-light (λ ≥ 400 nm) irradiation, the CoSe 2 /CdS 0.95 Se 0.05 nanocomposites exhibit significantly enhanced photocatalytic H 2 -evolution activities. The peak value of the H 2 -generation rate of 13894.8 μmol·h−1·g−1 is achieved with an apparent quantum efficiency (AQE) of 76.1%, which is approximate 66.7 times higher than that of pure CdS nanowires. Experimental investigations and theoretical calculations demonstrate that the enhanced photocatalytic H 2 -evolution performance originates from the synergetic effects of 1) the Se-doping to form CdS 0.95 Se 0.05 nanowires, which can reduce the electrostatic potential energy of CdS catalyst to promote electrons migration for reducing the recombination efficiency of electron/hole pairs; and 2) the in situ loading of CoSe 2 co-catalyst to construct the Schottky heterojunction between CoSe 2 and CdS 0.95 Se 0.05 nanowires, which can not only efficiently boost the separation of charge carriers, but also provide sufficient active sites for reducing H+ to H 2 subsequently. [ABSTRACT FROM AUTHOR]