<i>In Situ</i> Construction of Direct Z-Scheme Cd_0.8Mn_0.2S/NiTiO₃ Heterojunction for Photocatalytic Overall Water Splitting

Exploring low-cost, highly efficient, and stable semiconductor heterojunctions toward photocatalytic overall water splitting has garnered great interest. Herein, a solvothermal method is employed to in situ construct a novel direct Z-scheme heterojunction with hexagonal Cd0.8Mn0.2S (CMS) ultrafine nanorods decorated on perovskite NiTiO3 (NTO) rods. The resultant CMS/NTO(1:5) heterojunction with an optimal mass ratio in the presence of sacrificial hole scavenger delivers an apparent quantum yield (AQY) of 41.0% at 400 nm and a remarkable photocatalytic H2 yield of 1258 μmol h–1 under visible light (λ ≥ 420 nm) irradiation, 524 and 6.2 times higher than that of the NTO and CMS alone, respectively. This performance enhancement results from the constructed direct Z-scheme CMS/NTO heterojunction with close interfacial contact and its synergistic effect, which has efficient charge separation and transfer. After incorporating CoOx, the resultant CMS/NTO-CoOx(1:5) heterojunction in pure water exhibits photocatalytic overall water splitting activity with H2/O2 yields of 11.6/5.9 μmol h–1 under the full spectrum irradiation of a Xe-lamp. This study opens up new avenues for developing noble-metal-free artificial photosynthesis systems with efficient overall water splitting by coupling sulfide solid solutions with perovskite-type composite oxides.