Monomolecule Coupled to Oxygen-Doped Carbon for Efficient Electrocatalytic Hydrogen Peroxide Production.

Abstract

The electrocatalytic production of hydrogen peroxide (H₂O₂) is an ideal alternative for the industrial anthraquinone process because of environmental friendliness and energy efficiency, depending on the activity and selectivity of catalysts. Carbon-based materials possess prospects as candidate catalysts for the production of H₂O₂. Herein, cedar-derived monolithic carbon catalysts modified with coupling oxygen doping and phthalocyanine molecules are synthesized. Cobalt phthalocyanine (CoPc) molecules are introduced onto the carbon surface to construct monomolecular active sites via π-π stacking. The electronic structure of CoPc is modulated by oxygen doping on carbon substrates, mediated by monomolecular π-π stacking. A synergistic effect optimally modulated the interaction between CoPc and key intermediate to H₂O₂. The energy barrier for oxygen reduction is reduced to optimize the selectivity to H₂O₂. CoPc@OCW provided up to 99% selectivity to H₂O₂ at 0.7 V versus RHE. In a three-phase flow cell, CoPc@OCW achieved an H₂O₂ yield up to 10.4 mol·g^-1·h^-1 at 0.2 V versus RHE with stable running for 24 h. The advantages of carbon-based catalysts including the adjustable chemical structure depending on π-π stacking and electronic structure of carbon atoms through oxygen doping improved the catalytic performances in the production of H₂O₂. This proof-to-concept research demonstrates the potential application of carbon-based molecular catalysts for electrochemical synthesis.