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

Construction of a Visible-Light-Response Photocatalysis–Self-Fenton Degradation System of Coupling Industrial Waste Red Mud to Resorcinol–Formaldehyde Resin

“…In this route, H 2 O 2 can be synthesized in situ through the semiconductor photocatalysis without the need for external additions, effectively circumventing the risks associated with H 2 O 2 storage and transport. Photocatalytic H 2 O 2 production is generally considered a green and sustainable model owing to the boundless supply of solar energy [14,15]. Furthermore, H 2 O 2 formed spontaneously would be activated by Fe 2+ ions to produce • OH (Fe 2+ + H 2 O 2 → Fe 3+ + • OH + OH − , k = 40-80 L•mol −1 s −1 ); the produced Fe 3+ was further reduced by photo-generated electrons, which leads to the continuous Fenton effect due to the effective acceleration of Fe 2+ /Fe 3+ that recognized rate-limiting step in the Fenton reaction (Fe 3+ + H 2 O 2 → Fe 2+ + • OOH + H + , k = 0.001-0.01 L•mol −1 s −1 ) [16,17].…”

Recent advancements in graphitic carbon nitride based direct Z- and S-scheme heterostructures for photocatalytic H2O2 production

“…A number of semiconductors, namely metal oxides, 30 metal sulfides, 35–37 metal phosphides, 38,39 transition metal dichalcogenides, 40 transition metal oxyhydroxides, 41 metal–organic frameworks (MOFs), 42–44 carbon-based semiconductors, 45–47 metal-free organic semiconductors like g-C 3 N 4 , 48–50 resins, 51–58 covalent triazine frameworks (CTFs), 59 covalent organic frameworks (COFs), 60,61 covalent heptazine frameworks (CHFs) 62 and Bi-containing semiconductors, 63–65 have been extensively investigated for photocatalytic H 2 O 2 production. Despite significant research, the field still faces challenges such as low photoconversion efficiency and rapid e − /h + pair recombination, which limit its practical applications.…”