Our excessive consumption of fossil fuels is responsible for some of the major societal challenges we face, from climate change to pollution. Hydrogen is seen as a green alternative to fossil fuels, and alkaline water electrolysis is proving an attractive technology for commercializing large-scale hydrogen production.
However, current industrial applications of electrocatalytic water separation are limited by the high overvoltage of the oxygen evolution reaction (OER); an important electrochemical reaction in the process. This is especially true when operating at high electrical current densities (500-1000 mA cm-2). In a study published in the journal KeAi Green Energy & Environment, a group of Chinese researchers describe a process they developed to meet this challenge.
Professor Yunfei Bu from the China University of Information Science and Technology in Nanjing led the research. He explains, “Because OER involves four complex proton-electron coordination transfer steps in an alkaline medium, the level of proton-electron transfer you can achieve is limited. To solve this problem, we have built a simple and scalable proton acceptor strategy that reduces the size of proton acceptors at the molecular level and integrates them into the entire catalyst.
Yaobin Wang, a doctoral student at the same university, developed the new method, and according to co-author Dr. Feng Li, a professor at Fudan University of China, the reason it works so well is because the ” Molecular-level design increases the direct connection between the surface proton acceptor and the support, and solves the existing problems around a long transfer path, limited interface, and loose contact. improved proton transfer kinetics under high current.
The study also evaluated the water electrolysis performance of the catalyst under practical conditions, using a membrane-electrode assembly. According to the researchers, the electrolyzer can reach a high current density of 500 mA cm-2 or even 1000 mA cm-2 at low overpotential, and the global Faraday is close to 96%.
Professor Bu concludes: “This new strategy shows great application prospects in practical water electrolysis devices and high-current industrial applications. Moreover, this functional modification at the molecular level has the potential to be extended to more catalytic domains.