Temperature-Driven Morphology Control on CdSe Nanofractals and Its Influence over the Augmented Rate of H₂ Evolution: Charge Separation via the S-Scheme Mechanism with Incorporated Cu₃P

The thermodynamically controlled synthesis of dendritic fractals and nanorods via the hydrothermal reaction has been described, and their extensive photocatalytic hydrogen production properties under simulated solar light have been demonstrated. The long-range and short-range growth of CdSe monomers has been controlled by varying the reaction temperature from 100 to 200 °C. Changes in the physical and optical properties of prepared dendrites and nanorods have been evidently proven with microscopic analysis, diffuse reflectance spectroscopy, and BET analysis. A high-surface area CdSe dendritic fractal has been incorporated with bifunctional Cu3P nanoparticles that resulted in a highly efficient photocatalyst construction. Consequently, a pivotal upswing in the photocatalytic performance of CdSe was found by the formation of the S-scheme heterojunction with Cu3P. The unique properties of transition-metal phosphides kept them as a highly capable co-catalyst to replace precious metals. The physicochemical properties of the prepared materials were characterized by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The key challenge in the photocatalytic water splitting process is to develop an efficient photocatalyst not only with high chemical and photochemical stability but also with strong solar light absorption and effective charge separation ability. The co-catalyst Cu3P gives an effective path as it forms the S-scheme heterojunction with CdSe dendritic fractals. This enhances photoactivity and stability of the prepared composite. The composite made of CdSe and Cu3P showed a better rate of H2 production (92.1 mmol h–1 gcat–1) with 4% visible light to hydrogen conversion efficacy. The effects of Cu3P growth, size, and morphology of CdSe on the photocatalytic performance have been studied. Based on the material characterization and photocatalytic activity results, the working mechanism is also proposed.