Â鶹ÒùÔº

Scientists develop novel strategy to enhance water oxidation catalysis

A research team has developed a highly stable and efficient water oxidation catalyst, marking a major advancement in the field of green hydrogen production via water splitting technology.

Their study was in Science on April 25. The team was led by Prof. Yan Ya from the Shanghai Institute of Ceramics of the Chinese Academy of Sciences, in collaboration with scientists from Huazhong University of Science and Technology, Shanghai Jiao Tong University, and the University of Auckland.

Water oxidation—where water molecules are split into oxygen gas, protons, and electrons—is a key half-reaction in electrolytic water splitting. However, it remains a bottleneck due to its high energy consumption and sluggish kinetics, requiring highly efficient catalysts to overcome these barriers.

Although current transition metal-based catalysts exhibit good activity for alkaline water oxidation, they often degrade rapidly under industrial-level high current densities, primarily due to structural distortion and the dissolution of active metal sites under strong oxidative conditions.

To tackle this challenge, the researchers proposed an innovative strategy to balance the high catalytic activity and durability simultaneously under industrial-level high current densities. By targeting grafting, the CoFe metal-organic frameworks (MOF) on Ni-bridged polyoxometalates (POMs), they constructed an MOF@POM superstructure.

Under water oxidation conditions, the CoFe-MOF undergoes an in-situ transformation into a single-layer CoFe-layered double hydroxide (CoFe-LDH), covalently bonded to POM units through Ni–O bridges. Thus, a highly active and stable single-layer CoFe hydroxide superstructure catalyst was successfully achieved.

In-situ electrochemical spectroscopy revealed a synergistic catalytic process between Co and Fe active sites and Ni and W tuning centers. The valence states of catalytic active cobalt and iron increase progressively during operation, while the Ni–O and W–O tuning components undergo dynamic valence oscillations.

The systematic analysis showed that the POM units play a critical role in stabilizing the catalyst by modulating electron density and relieving lattice strain, together forming a synergistic strain–electron dual stabilization mechanism, and effectively stabilizing the catalyst under extreme conditions.

The CoFe-LDH@POM catalyst demonstrated exceptional performance in alkaline electrolytes, requiring only 178 mV overpotential at 10 mA/cm², outperforming conventional transition metal-based catalysts. When integrated into an anion exchange membrane electrolyzer, the device displayed 3 A/cm² current density with a cell voltage of only 1.78 V at 80 °C, exceeding the U.S. Department of Energy's 2025 industrial target.

Long-term tests further underscored the system's robustness. The electrolyzer operated stably for over 5,140 hours at 2 A/cm² under room temperature, with a minimal voltage decay rate of just 0.02 mV/h. Even at an elevated temperature of 60 °C, the system maintained continuous operation for more than 2,000 hours.

This work not only sets a new benchmark for high-performance water oxidation catalysts but also establishes a design framework for next-generation electrocatalysts, advancing alkaline water electrolysis toward industrial-scale, high-current, low-energy operation.