Strongly coupled 2D-2D nanojunctions between P-doped Ni₂S (Ni₂SP) cocatalysts and CdS nanosheets for efficient photocatalytic H₂ evolution

Developing low-cost, environment-friendly and highly-active nanocomposites for photocatalytic hydrogen evolution reaction (HER) holds pivotal function in water splitting. Supported cocatalysts on semiconductor can facilitate speedy transfer and separation of photoexcited charge, active interfacial response and suppress photocorrosion. We, for the first time, proposed a novel strategy to formed 2D-2D (two dimensional) nanocomposites by loading 2D P-doped Ni₂S (Ni₂SP) cocatalysts onto 2D CdS nanosheets (NSs). The as-obtained 2D-2D CdS/Ni₂SP nanocomposites exhibited excellent HER activity in 0.25 M Na₂S-Na₂SO₃ sacrificial solution under visible light (λ ≥ 420 nm). The optimal loading of 2 wt% 2D Ni₂SP on 2D CdS as a cocatalyst yielded an optimal H₂ production rate at 18.96 mmol g⁻¹ h⁻¹, which was approximately 3.26 folds higher than that of bare 2D CdS (5.82 mmol g⁻¹ h⁻¹) without cocatalysts. In the presence of non-precious metal, the highest apparent quantum efficiency of 4.8% was recorded at 420 nm. The enhanced photocatalytic HER activity was attributed to the excellent interfacial coupling effects of Ni₂SP NSs cocatalyst with CdS NSs, which was essential for the rapid charge separation and transfer, increased number of active sites and improved H₂-evolution kinetics. This study offers a feasible scheme to design efficient photocatalysts system to produce hydrogen.