Electrochemical production of hydrogen peroxide (H 2 O 2 ) constitutes a cost-effective and alternative method to the complex and energy-intensive anthraquinone oxidation process. The two-electron water oxidation reaction pathway, while unconventional, is an attractive option for H 2 O 2 generation as it can be combined with suitable reduction reactions to effectuate simultaneous electrosynthesis of valuable chemicals at a large scale. In this work we demonstrate that a carbon-based catalyst, boron-doped diamond (BDD), achieves an H 2 O 2 concentration and production rate of 29.0 mmol dm −3 and 19.7 μmol min −1 cm −2 , respectively, illustrating the capability of BDD as a suitable electrocatalyst for H 2 O 2 formation from water.

The two-electron water oxidation reaction (2e – WOR) is progressively gaining traction as a sustainable approach for in situ electrosynthesis of hydrogen peroxide (H2O2). State-of-the-art 2e – WOR electrocatalysts have shown great promise at low electrical currents yet exhibit diminished electrocatalytic capabilities at larger current densities. Herein, by tailoring the boron doping level of boron-doped diamond (BDD) microfilms, we have fabricated an active, selective, and stable electrocatalyst for the 2e – WOR. Experimentally, we find that our modulated BDD films achieve a peak faradaic efficiency of 87%, as well as a record H2O2 production rate of 76.4 μmol cm–2 min–1, while maintaining a stable electrochemical performance for 10 h at 200 mA cm–2 in carbonate-based solutions. The results reported in this work firmly establish BDD as a primary catalyst candidate for large-scale implementation of the 2e – WOR and synchronously unlock new research avenues for the next-generation design of sp3-structured carbonaceous materials for anodic H2O2 electrosynthesis from water.

Electrochemical production of hydrogen peroxide (H2O2) has recently gained traction as a green alternative to the unsustainable anthraquinone auto-oxidation process and the high-risk direct synthesis route. While the two-electron oxygen reduction reaction (2e – ORR) toward H2O2 has been covered extensively in the literature, the unorthodox two-electron water oxidation reaction (2e – WOR) remains far less popular, due to the thermodynamic unfavorability of the pathway. Nonetheless, the 2e – WOR constitutes a coveted procedure as it enables the electro-generation of H2O2 solely from water. A thorough understanding of the reaction mechanism, including all intermediates and competing reaction routes, is essential for the fabrication of electrocatalysts, and assembly of electrochemical reactors, capable of greater H2O2 production rates with an optimal efficiency. This review focuses exclusively on the 2e – WOR to electrochemically produce H2O2. A summary of all prevailing water oxidation mechanisms is presented, supported with computational and experimental data, and key challenges and limitations that require attention are addressed.

Electrochemical synthesis of hydrogen peroxide (H2O2), via the two‐electron water oxidation reaction (2e− WOR), is an attractive method for the sustainable production of valuable chemicals in place of oxygen during water electrolysis. While the majority of 2e− WOR studies have focussed on electrocatalyst design, little research has been carried out on the selection of the supporting electrolyte. In this work, we investigate the impact of potassium carbonate (K2CO3) electrolytes, and their key properties, on H2O2 production. We found that at electrolyte pH values (>9.5) where the carbonate anion (CO32−) was prevalent in the mixture, a 26.5 % increase in the Faraday efficiency (%FE) for H2O2 production was achieved, compared to bicarbonate (HCO3−) dominant solutions. Utilising boron‐doped diamond (BDD) in highly concentrated K2CO3 solutions, current densities of up to 511 mA cm−2 (in 4 m) and %FEs of 91.5 % (in 5 m) could be attained. The results presented in this work highlight the influence of CO32− on electrochemical H2O2 generation via the 2e− WOR and provide novel pathways to produce desirable commodities at the anode during electrochemical water splitting.

H2O2 is an important chemical with multiple uses across domestic and industrial settings. A global need for wider adoption of green synthetic methods, there has been a growing interest in the electrochemical synthesis of H2O2 from oxygen reduction or water oxidation. State of the art catalyst and reactor developments are beginning to advance to a stage where electrochemical synthesis is discussed as a viable alternative to current industrial methods. In this review, we highlight some of the most promising candidates for H2O2 electrosynthesis technologies, and what further advancements are needed before the electrochemical route could challenge the ubiquitous anthraquinone process.