A ternary dumbbell MoS₂ tipped Zn_0.1Cd_0.9S nanorods visible light driven photocatalyst for simultaneous hydrogen production with organics degradation in wastewater

Despite photocatalytic hydrogen (H₂) production coupled with organic degradation in wastewater being considered a promising and synergistic redox process, achieving the desired results is still be significant challenge. In this project, we rationally designed a photocatalytic system comprising the MoS₂ nano flower tipped Zn_0.1Cd_0.9S nanorods (NRs) with strategic use of soft templates to enhance photocatalytic H₂ production with organic degradation in wastewater. The optimized photocatalytic system, referred to as MTZC-2, achieved an exceptional photocatalytic H₂ production rate of 11.01 mmol g⁻¹ h⁻¹ using Na₂S·9H₂O/Na₂SO₃ as a sacrificial reagent, which was 4.22 times greater than that of pure Zn_0.1Cd_0.9S NRs (2.61 mmol g⁻¹ h⁻¹). When replacing the sacrificial reagent with organic wastewater, the system maintained a photocatalytic H₂ production rate of 525 μmol g⁻¹ h⁻¹ while achieving 99 % degradation of 20 ppm ofloxacin (OFX) within 2 h. Furthermore, this system exhibited an extraordinary apparent quantum efficiency (AQE) of 4.69 % under monochromatic light at 450 nm for H₂ production. The development of the Schottky barriers and spatial separation of reaction sites plays a crucial role in enhancing photoactivity and effectively inhibiting the annihilation of photoexcited electron-hole pairs and Cd²⁺ leaching. This unique structure is strategically useful for adsorption and surface reactions with organic degradation at the Zn_0.1Cd_0.9S NRs stem and H₂ production at the MoS₂ nano flower, confirmed through Pt photo deposition and kelvin probe force microscopy (KPFM) test. Further, density functional theory (DFT) calculations revealed the optimized photocatalytic system has Gibbs free energy of hydrogen adsorption (ΔG_H^∗) near zero which also supports the efficient photocatalytic H₂ production at the tip of NRs via directional transfer of photoexcited charge carriers in the system. This work based on the idea of catching two fish with one hook could be an encouraging effort for the development of novel and efficient dual-functional photocatalysts.