【Frontiers in HaiChuan Chemical Technology】Achieving efficient acidic water electrolysis for hydrogen production through electron confinement at the surface of armored catalysts

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I achieved efficient acidic water electrolysis for hydrogen production through the surface electron confinement effect of armored catalysts. Publication date: 2025-06-11 | Contributing department: Group 509 | [Enlarge] [Shrink] | [Print] [Close] Recently, a team led by researchers Deng Dehui and Yu Liang from the Energy and Environment Small Molecule Catalysis Research Center of our institute’s National Key Laboratory of Energy Catalytic Conversion (Group 509), in collaboration with Professor Lu Junling’s team from the University of Science and Technology of China and a team led by researcher Yu Hongmei from our institute’s research group on efficient water electrolysis for hydrogen production (Group DNL0325), discovered that the asymmetric π-electrons concentrated on the surface of armored catalysts possess a unique confinement effect that can simultaneously enhance the activity and stability of surface-confined platinum (Pt) atoms. Based on this, the collaborating team designed and synthesized a highly active and stable catalyst for water electrolysis to produce hydrogen. They also assembled a kilowatt-scale proton exchange membrane electrolyzer, thereby achieving efficient acidic water electrolysis at ultra-low Pt loading and high industrial current densities. Proton exchange membrane water electrolysis (PEMWE) is one of the key technologies for large-scale production of green hydrogen. The precious metal Pt has a moderate hydrogen binding energy and excellent resistance to acid corrosion; therefore, platinum/carbon (Pt/C) is commonly used as the cathode catalyst in commercial PEMWE. However, under conditions of prolonged operation or high reduction potentials, the Pt nanoparticles in the Pt/C catalyst tend to aggregate or detach from the support, resulting in a decrease in the number of active sites and a decline in overall catalytic performance. To maintain an efficient and long-lasting electrolytic water generation process, it is often necessary to increase the Pt loading, which significantly raises the cost of the catalyst. In this work, the team discovered that in the catalyst structure of cobalt-nickel (CoNi) nanocomposite armor encapsulated by single-layer graphene, the electron transfer from metals to carbon and the electron interactions between metals and graphene can generate enriched asymmetric π-electron states on the surface of the graphene armor. Using atomic layer deposition technology, the team achieved the precise deposition of single-atom Pt at the asymmetric π-electron-rich sites on the surface of the graphene armor. Studies combining various in-situ spectroscopic methods and theoretical calculations have revealed that this asymmetric π-electron pair exerts a unique electron confinement effect on the Pt atoms: on one hand, the CoNi nanocomposite facilitates electron transfer from the graphene shell to the Pt atoms, resulting in a more electron-rich state for Pt; this improves the hydrogen adsorption energy at the Pt sites, promotes hydrogen desorption, and enhances the electrocatalytic hydrogen evolution activity at these sites ； On the other hand, the asymmetric π electrons enriched on the graphene surface form strong interactions with the 5d orbitals of Pt, enhancing the structural stability of the Pt sites. The PEMWE electrolyzer assembled by the team using this novel armor catalyst can achieve a current density of 4.0 A cm−2 at a cell voltage of 2.02 V (without iR compensation). It also operates stably for over 1,000 hours at a current density of 2.0 A cm−2. The Pt loading on the cathode side of this electrolyzer is merely 1.2 μgPt cm−2. In further scale-up experiments, the 2.85 kW PEMWE electrolyzer assembled using this catalyst also exhibited excellent catalytic activity and stability, operating stably for over 300 hours at an industrial current density of 1.5 A cm−2, demonstrating great potential for industrial application. This work provides new insights for the development of high-performance, long-lasting, and low-cost catalysts for acidic electrolytic water splitting to produce hydrogen. The team led by Deng Dehui has long been committed to research on the surface and interface modulation of two-dimensional catalytic materials. Based on the structure of graphene-encapsulated metal nanoparticles, they proposed the concept of “armored catalysis” internationally. They have also conducted systematic research on the structural design of armored catalysts and the regulation of their catalytic performance