Electrosynthesis of hydrogen peroxide using modified gas diffusion electrodes (MGDE) for environmental applications: Quinones and azo compounds employed as redox modifiers

Highly efficient electrosynthesis of hydrogen peroxide on a superhydrophobic three-phase interface by natural air diffusion

“…18). In the absence of additional air-pumping equipment, the production of H 2 O 2 decreased as the current density increased due to the seepage on normal GDE and parallel reactions resulting in decomposition of H 2 O 2 23 .…”

Tailoring the ORR selectivity for H2O2 electrogeneration by modification of Printex L6 carbon with 1,4-naphthoquinone: a theoretical, experimental and environmental application study

“…18,19,24 The electrogeneration of H 2 O 2 typically occurs through the application of carbonaceous materials -usually carbon black -as a cathode in the electrolyte matrix with pressurized O 2 gas. 18,[24][25][26] Printex L6 (PL6C) is a carbon black pigment employed as a high efficiency electrocatalytic matrix for H 2 O 2 electrogeneration; its good performance can be attributed to corrosion resistance, large surface area (265 m 2 g À1 ) and oxygenated functional groups (-C-OOH, -CQO, -C-OH). 27 Furthermore, the hydrophobicity of PL6C, associated with the role in the oxygen reduction reaction (ORR), provides high selectivity for H 2 O 2 28,29 and makes it ideally suitable for the application of O 2 gas at the electrolyte/electrode interface in GDE reactions.…”

“…In order to improve the ORR activity toward H 2 O 2 production, some authors have proposed different techniques for modifying carbon-based materials, including the use of metallic oxides, [35][36][37] metallic complexes, 19,32 metallic nanoparticles 38,39 and organic compounds. 18,26,[40][41][42] These modifications can lead to a decrease of the overpotentials required for the ORR and an improvement of oxygen supply in solution, increasing the H 2 O 2 generation.…”

“…In this sense, several studies published in the literature have thoroughly investigated the use of quinones as modifiers of carbon matrices for H 2 O 2 production. 18,26,47,48 The advantage being that the mechanism for the ORR involves two-electron transfer, favouring H 2 O 2 production. However, the mechanism for H 2 O 2 electrogeneration is still not clearly understood.…”

“…18 More recently, Moreira et al (2019) reported the use of 2% anthraquinone-2carboxylic acid in a carbon matrix (w/w), which led to greater current efficiency in H 2 O 2 electrogeneration compared to the unmodified carbon electrode. 26 Although these authors have demonstrated the crucial contribution of quinones as modifiers of the carbonaceous matrix, the mechanism has not been thoroughly clarified.…”