Synergistic Use of a Solid Solution and a Cocatalyst on Co_xCd_1–xS/Ni_yFe_1–y-LDH for Efficient and Stable Photoelectrochemical Performance

Cadmium sulfide (CdS)-based photoelectrodes have been extensively studied in photoelectrochemical (PEC) water splitting, but these semiconductors still suffer from low photogenerated carrier separation efficiency and poor photostability. Herein, we synthesized and explored a CoxCd1–xS/NiyFe1–y-LDH composite photoanode composed of a CoxCd1–xS solid solution and a NiyFe1–y-LDH cocatalyst. Compared with the pristine CdS film, the synthesized Co0.30Cd0.70S/Ni0.50Fe0.50-LDH composite film has optimum PEC activity and photostability in the process of water oxidation due to the synergism of the solid solution and the cocatalyst. First, the Co0.30Cd0.70S solid solution doped with an appropriate amount of Co2+ can not only effectively absorb photons but also maximize the utilization of photons, thereby improving the PEC performance. Second, Ni0.50Fe0.50-LDH in the outer layer of the Co0.30Cd0.70S/Ni0.50Fe0.50-LDH photoanode promotes the reaction kinetics of surface oxygen production of Co0.30Cd0.70S, which further improves the carrier density and the separation efficiency of photogenerated carriers. Meanwhile, the Ni0.50Fe0.50-LDH cocatalyst quickly captures and transports photogenerated holes to promote the photocorrosion resistance of Co0.30Cd0.70S. This study provides a path to synthesize the highly efficient and stable CdS-based photoanode by the synergistic use of a solid solution and a cocatalyst for PEC water splitting.