3‐Hydroxythiophenol‐Formaldehyde Resin Microspheres Modulated by Sulfhydryl Groups for Highly Efficient Photocatalytic Synthesis of H₂O₂

Abstract

Resorcinol‐formaldehyde (RF) resin represents a promising visible‐light responding photocatalyst for oxygen reduction reaction (ORR) toward H₂O₂ production. However, its photocatalytic ORR activity toward H₂O₂ generation is still unsatisfied for practical application. Herein, 3‐hydroxythiophenol‐formaldehyde (3‐HTPF) resin microspheres synthesized through polycondensation reaction between 3‐HTP and formaldehyde at room temperature and subsequent hydrothermal treatment exhibit enhanced photocatalytic ORR activity is reported. The experimental results show that the partial substitution of hydroxy group (─OH) by sulfhydryl one (─SH) through using 3‐HTP to replace resorcinol could slow the rates of nucleation and growth of the resin particles and lead to strongly π‐stacked architecture in 3‐HTPF. The introduction of ─SH group can also improve adsorption ability of 3‐HTPF to O₂ molecules and enhance ORR catalytic activity of the photocatalysts. Stronger built‐in electric field, better adsorption ability to O₂ molecules, and increased surface catalytic activity collectively boost photocatalytic activity of 3‐HTPF microspheres. As a result, H₂O₂ production rate of 2010 µ

 h⁻¹ is achieved over 3‐HTPF microspheres at 273 K, which is 3.4 times larger than that obtained using RF submicrospheres (591 µ h⁻¹). The rational substituent group modulation provides a new strategy for designing polymeric photocatalysts at the molecular level toward high‐efficiency artificial photosynthesis.