Engineering a NiAl-LDH/CoS_x S-Scheme heterojunction for enhanced photocatalytic hydrogen evolution

The use of semiconductors to construct heterojunctions to suppress the rapid recombination of photogenerated charges and holes is considered to be an effective way to improve the efficiency of photocatalytic hydrogen evolution. Herein, cobalt sulfide (CoS_x) nanoparticles are cultivated in situ in the folds of three-dimensional flower-like nickel-aluminium layered double hydroxides (NiAl-LDHs) using a facile solvothermal method. The hydrogen production rate of the binary CoS_x/NiAl-LDH heterojunction reaches 3678.59 μmol/g/h, which is 83.74 and 22 times the rates of CoS_x and NiAl-LDH, respectively. The unique three-dimensional structure of NiAl-LDH facilitates the growth of CoS_x and shortens the transfer pathway of photogenerated electrons. More importantly, the built-in electric field formed at the interface and the S-type charge transport mechanism caused by the bending of the energy band enhance not only charge separation but also maintain the strong oxidation ability of the holes. In this study, the newly designed S-scheme heterojunction offers a new strategy for enhancing photocatalytic water splitting.