MOFs derived CdS/CdO heterojunction photoanode for high-efficient water splitting

• Porous CdS/CdO-M photoanodes were prepared by facile annealing Cd-MOF and SILAR method. • The optimized catalyst demonstrated excellent photoelectrochemical (PEC) water splitting efficiency and long-time stability. • The pores and heterojunction in CdS/CdO-M photoanodes contributed to their excellent PEC water splitting performance. • The work provides a feasible strategy for fabricating effective photoelectrodes. Enabling the photogenerated electron-hole separation of visible light responsive photoanode is essential to the conversion and utilization of solar energy in the photoelectrochemical (PEC) water splitting. In this study, porous CdS/CdO-M heterojunction photoanodes on fluorine-doped tin oxide glasses were prepared by calcining the Cd-metal-organic framework (Cd-MOF) and loading the CdS via successive ionic layer adsorption and reaction method. The heterojunction and pores in these prepared photoanodes promoted the separation and transfer of photogenerated electron-hole in the PEC water splitting. The optimized photoanode (CdS/CdO-M-15) exhibited superior photoelectrochemical water splitting performance with a photocurrent density of 4.8 mA cm −2 , which is 20, 6 and 1.5 times higher than that of CdO-M, CdS and CdS/CdO-C-15 (prepared by the commercial CdO). The applied bias photon-to-current conversion efficiency of CdS/CdO-M-15 was as highly as 4.5% under simulated solar light of 100 mW cm −2 in 0.25 M Na 2 S + 0.35 M Na 2 SO 3 aqueous solution. Moreover, CdS/CdO-M-15 was stable under continuous illumination, and its photocurrent density for it was well maintained after 1 h illumination.