Enhanced photocatalytic hydrogen evolution by polyiodide-boosted electron transport and Pt–Ag alloy active sites in conductive polymer-based core–shell photocatalysts

Abstract

The photocatalytic hydrogen evolution reaction (HER) represents a promising route for sustainable solar-to-hydrogen conversion; however, practical implementation is often constrained by inefficient charge transport and high noble-metal requirements. Here, we report a core–shell photocatalyst, Fe₃O₄@PPy@Pt/Ag@I, designed with a sustainability-oriented strategy that simultaneously addresses three critical challenges: resource-efficient use of noble metals, enhanced charge-transport efficiency, and operational recyclability. The in situ formation of Pt–Ag alloy nanodots reduces reliance on pure Pt while retaining high catalytic activity, improving noble-metal utilization efficiency. Polyiodide species (I₃⁻ and I₅⁻) embedded within the polypyrrole (PPy) matrix facilitate efficient electron transport. The synergistic combination of polyiodide-assisted charge transfer and Pt–Ag alloy-mediated proton reduction enhances charge separation, prolongs carrier lifetimes, and accelerates HER kinetics, resulting in a 6.2-fold increase in the hydrogen-evolution rate and substantially improved Pt mass activity relative to Fe₃O₄@PPy@Pt. In addition, the magnetic Fe₃O₄ core enables facile recovery and reuse of the catalyst, demonstrating a cost-effective and sustainability-driven approach for conductive polymer-based photocatalytic hydrogen production.