Researchers from the Korea Institute of Science and Technology (KIST) have developed a highly efficient carbon catalyst that can effectively produce green hydrogen peroxide.
Importantly, it works even in air supply environments with low oxygen concentrations and neutral electrolytes by introducing mesopores into the carbon catalyst.
This breakthrough overcomes a tricky limitation in green hydrogen production, as it has often been limited by the high cost of injecting high-purity oxygen gas.
Difficulties in producing hydrogen peroxide
Hydrogen peroxide is one of the world’s top 100 industrial chemicals with a wide range of applications in the chemical, medical, and semiconductor industries.
Currently, hydrogen peroxide is mainly produced through the anthraquinone process, but this process has several problems, including high energy consumption, the use of expensive palladium catalysts, and environmental pollution due to by-products.
In recent years, an environmentally friendly method of producing hydrogen peroxide by electrochemical reduction of oxygen using inexpensive carbon catalysts has gained attention.
However, this method has been limited by the high cost of injecting high-purity oxygen gas and the practical limitations that the generated hydrogen peroxide is mainly produced in an unstable basic electrolyte environment.
Facilitating the smooth transfer of oxygen
The team synthesised boron-doped carbon with mesopores of about 20 nanometres by reacting the greenhouse gas carbon dioxide (CO₂), the potent reducing agent sodium borohydride (NaBH₄), and meso-sized calcium carbonate (CaCO₃) particles, followed by selective removal of the calcium carbonate particles.
Using it as a carbon catalyst for electrochemical hydrogen peroxide production, experiments and calculations have shown that the curved surface characteristics formed by the mesopores provide excellent catalytic activity even in neutral electrolyte environments, where hydrogen peroxide production reactions are difficult.
(Left) Schematic representation of the structure of a porous carbon catalyst with boron doping on the surface and carbon walls forming the mesopores
(Right) Mesopore structure and atomic-scale distribution of boron in the carbon catalyst measured using transmission electron microscopy and atomic force microscopy
Furthermore, real-time Raman analysis has confirmed that the mesoporous structure facilitates the smooth transfer of oxygen as a reactant, allowing high catalytic activity to be maintained even in air environments with an oxygen concentration of only about 20%.
The new carbon catalyst is extremely efficient
Based on these findings, the team demonstrated that boron-doped mesoporous carbon catalysts, when applied to a hydrogen peroxide mass production reactor, can achieve world-class hydrogen peroxide production efficiencies.
These efficiencies can exceed 80% under near-commercial conditions of neutral electrolyte and air supply and industrial-scale current density (200 mA/cm²).
In particular, the team succeeded in producing hydrogen peroxide solutions with a concentration of 3.6%, which exceeds the medical hydrogen peroxide concentration (3%), suggesting the possibility of commercialisation.
Dr Jong Min Kim from KIST stated: “The mesoporous carbon catalyst technology, which utilises oxygen from the air we breathe to produce hydrogen peroxide from a neutral electrolyte, is more practical than conventional catalysts and will speed up industrialisation.”
The future of commercialised carbon catalysts
The future research implications of this study are significant in advancing sustainable and efficient methods for hydrogen peroxide production.
The development of boron-doped mesoporous carbon catalysts capable of producing green hydrogen peroxide in air-supplied, neutral electrolyte environments opens avenues for scaling up the process, reducing energy consumption, and minimising the environmental impact compared to conventional methods.
Future research could focus on optimising the catalyst structure and composition further to enhance its efficiency, stability, and cost-effectiveness.
Additionally, exploring the integration of this technology into industrial-scale applications, such as large-scale reactors, could help address the challenges of commercial hydrogen peroxide production, leading to more sustainable processes across various industries.
