A Synergistic Combination of P‐doped Zn_0.5Cd_0.5S and CoP for Dual‐Stage Electron Trapping and Its Application in Seawater Splitting

Over the years, researchers have placed increasing focus on extending the application of photocatalytic hydrogen (H₂) evolution to seawater. Herein, a photocatalytic system with a unique combination of P‐doped Zn_0.5Cd_0.5S (pZCS) and noble‐metal‐free CoP is first fabricated to evaluate the synergy between them. The resultant sample achieves a significantly boosted photocatalytic H₂ evolution reaction (HER) with a rate of 5488.8 μmol g⁻¹ h⁻¹, which is an almost 50‐fold enhancement from its pristine ZCS counterpart. Impressively, the CoP–pZCS composite also demonstrates overall water splitting where no sacrificial reagent is used, with an H₂ evolution rate of 154.6 μmol g⁻¹ h⁻¹. The sample is then tested for its HER activity in seawater, and 3956.0 μmol g⁻¹ h⁻¹ of H₂ is acquired. The main factor that contributes to its high performance in seawater despite various distractions coming from the abundance of ions present is the synergistic relation between pZCS and CoP. The midgap state procured through the introduction of the P dopant has excellent electron–hole separating ability, and CoP further serves as an electron sink where the photogenerated electrons can rapidly assemble. Ultimately, the charge carrier recombination within the resultant composite is greatly hindered, thus a spectacular photocatalytic HER in seawater is enabled.