Metal–organic Framework-Derived CoSx/NiS Co-Decorated Heterostructures: Toward Simultaneous Acceleration of Charge Carrier Separation and Catalytic Kinetics

Designing semiconductor-based heterojunctions for achieving high-efficiency electron–hole separation and rapid catalytic kinetics is highly important for promoting photoelectrochemical water oxidation performance. Herein, we synthesize a dual-cocatalyst-decorated heterostructure (TiO2/CdS/CoSx/NiS) via in situ metal–organic framework (MOF) derivation. The homogeneous dispersion of CoSx/NiS, benefiting from the MOF derivation of atomic metal building blocks, significantly accelerates the catalytic kinetics and decreases the overpotential of the water oxidation process. Meanwhile, the CoNi MOF-derived TiO2/CdS heterojunctions simultaneously improve the electron–hole separation and extend the absorption range due to the formation of an oriented electromagnetic field and narrow bandgap of CdS. The as-prepared TiO2/CdS/CoSx/NiS exhibits excellent performance toward photoelectrochemical water oxidation with a photocurrent density of up to 5.10 mA/cm2. The practical production rate of O2 is about 22.25 μmol·h–1·cm–2, which is higher than those of TiO2/CoNi-MOF (18.69 μmol·h–1·cm–2) and bare TiO2 (13.80 μmol·h–1·cm–2). This study offers a promising solution to tailor the growth and dispersion of high-quality dual-cocatalysts and paves the way toward the commercial realization of water-splitting systems.