Enhanced in-situ electrosynthesis of hydrogen peroxide on a modified active carbon fiber prepared through response surface methodology

Abstract

• The preparing condition of g-C 3 N 4 /CNTs/ACF was optimized by response surface methodology. • The introduction of g-C 3 N 4 alleviated adsorption energy of oxygen and coordinated ∗ OOH binding capability. • The defects on CNTs could also reduce the oxygen adsorption energy and CNTs simultaneously increases the conductivity of the electrodes. • An appropriate amount of PTFE constructed a gas–liquid-solid three phase equilibrium, promoting the oxygen diffuse on the carbon fiber surface. • The effects of operating parameters on the production of H 2 O 2 were discussed specifically. Electrosynthesis of hydrogen peroxide (H 2 O 2 ) by two-electron oxygen reduction on the cathode is an attractive green approach for environmental remediation and chemical industries. In this study, an active carbon fiber (ACF) electrode modified with graphite carbon nitride (g-C 3 N 4 ) and carbon nanotubes (CNTs) is fabricated by a wet ultrasonic impregnation-calcination method. The doping content of g-C 3 N 4 , CNTs and polytetrafluoroethylene (PTFE) is optimized by response surface methodology (RSM). With optimum doping content, the H 2 O 2 generation by modified ACF increased several times, indicating the physicochemical and electronic transformation of ACF. The introduction of g-C 3 N 4 modulates the electronic structure of ACF, alleviating the adsorption energy of oxygen and coordinating the ∗ OOH binding capability. Besides reducing the oxygen adsorption energy, CNTs simultaneously improve the conductivity of electrodes. In addition, the addition of an appropriate amount of PTFE constructs a gas–liquid-solid three-phase equilibrium, facilitating oxygen diffusion. The effects of operating parameters on H 2 O 2 generation are also investigated and the optimal performance is achieved at current = 0.2 A, pH = 3, and aeration rate = 0.32 L/min. The modified ACF shows great potential in the practical applications for in-situ H 2 O 2 electro-generation.