Rational design of 1D NiMoO4/0D CdS heterostructures for efficient photocatalytic hydrogen generation under visible light

Abstract

Solar-driven hydrogen production via particulate photocatalysts is a sustainable and promising way for overcoming the current energy crisis. In this work, CdS nanoparticles were synthesized via the precipitation method and then decorated hydrothermally by NiMoO₄ nanorods. The as-prepared CdS-NiMoO₄ nanocomposite showed an initial hydrogen generation rate (HGR) of 130 μmol h⁻¹ under the visible spectrum. This represents a 7-fold increase compared to that of pure CdS. Increasing the hydrothermal treatment temperature of the nanocomposite above 90 °C was found to have a negative impact on the H₂ production efficiency. The prepared composite was subjected to various photoelectrochemical measurements for investigating the photoelectric properties and the proposed mechanism. The results revealed that CdS and NiMoO₄ semiconductors have well-established band structures to form a type-II heterojunction. Thus, NiMoO₄ works as an electron collector that captures the photogenerated electrons from CdS, thereby promoting the separation of e⁻/h⁺ pairs. The improvement in the catalytic performance could also be attributed to the increase in the active catalytic sites of CdS-NiMoO₄ (S_BET = 335.7 m² g⁻¹) compared with CdS (S_BET = 225.5 m² g⁻¹). Overall, this work sheds light on using earth abundant NiMoO₄ as an effective promoter in photocatalytic applications.