Dipole–Dipole Tuned Electronic Reconfiguration of Defective Carbon Sites for Efficient Oxygen Reduction into H₂O₂

Abstract

Metal‐free carbon‐based materials are one of the most promising electrocatalysts toward 2‐electron oxygen reduction reaction (2e‐ORR) for on‐site production of hydrogen peroxide (H2O2), which however suffer from uncontrollable carbonizations and inferior 2e‐ORR selectivity. To this end, a polydopamine (PDA)‐modified carbon catalyst with a dipole–dipole enhancement is developed via a calcination‐free method. The H2O2 yield rate outstandingly reaches 1.8 mol gcat−1 h−1 with high faradaic efficiency of above 95% under a wide potential range of 0.4–0.7 VRHE, overwhelming most of carbon electrocatalysts. Meanwhile, within a lab‐made flow cell, the synthesized ORR electrode features an exceptional stability for over 250 h, achieved a pure H2O2 production efficacy of 306 g kWh−1. By virtue of its industrial‐level capabilities, the established flow cell manages to perform a rapid pulp bleaching within 30 min. The superior performance and enhanced selectivity of 2e‐ORR is experimentally revealed and attributed to the electronic reconfiguration on defective carbon sites induced by non‐covalent dipole–dipole influence between PDA and carbon, thereby prohibiting the cleavage of O–O in OOH intermediates. This proposed strategy of dipole–dipole effects is universally applicable over 1D carbon nanotubes and 2D graphene, providing a practical route to design 2e‐ORR catalysts.

Advanced Carbon Electrocatalysts for Selective Oxygen Reduction into Hydrogen Peroxide: Understandings of Active Sites

“…Despite of functionalization, another strategy of surface modifications is combining macromolecules with carbons, such as organic chains and polymers. Inspired by such concepts, our group innovatively proposed a polymer-carbon modification route, which improved 2e-ORR selectivity by establishing polydopamine (PDA)defective carbon (CB-PDA-A) electrocatalytic system [53]. The FE of the CB-PDA-A reached nearly 100% at 0.5 V RHE , harvesting an industrial-level H 2 O 2 yield of 1.8 mol g cat −1 h −1 .…”

“…It could also be governed by innovative designs on device and electrolyte types, which is however beyond the scope of this review [105][106][107]. the ORR selectivity with dipole-dipole interaction [53]. (e) A simplified reaction pathways at carbonyl and carboxyl sites.…”

Construction of dangling and staggered stacking aldehyde in covalent organic frameworks for 2e− oxygen reduction reaction

“…[42][43][44][45][46][47] Electrosynthesis of hydrogen peroxide (H 2 O 2 ) via 2e − ORR is considered as the ideal candidate for the indirect energy-intensive anthraquinone process, because of its low cost and high efficiency. [48][49][50][51][52][53][54][55][56] Oxygen-doped carbons were identified as one of the most effective metal-free catalysts toward 2e − ORR. [57][58][59] Till now, various fabrication approaches have been proposed to introduce oxygen functional groups (C-OH, C═O, and COOH) onto carbon surfaces.…”

Hf-Doped CoP Hollow Nanocubes as High-Performance Electrocatalyst for Oxygen Evolution Reaction

“…In recent years, hollow structures have attracted increasing research interest for a wide range of applications owing to their unique structures and inherent physical and chemical properties. − Metal-organic frameworks (MOFs) show great performance advantages in various applications. − Etching causes MOFs more defects, which can facilitate the doping of heteroatoms into MOFs, resulting in improved performance. , To date, there are different types of structures after etching MOF, such as core–shell structure − and nanosheet structure. − However, the selective directional etching of MOFs is rarely studied.…”