Water splitting is a promising approach to the efficient and cost-effective production of renewable fuels, but water oxidation remains a bottleneck in its technological development because it largely relies on noble-metal catalysts. Although inexpensive transition-metal oxides are competitive water oxidation catalysts in alkaline media, they cannot compete with noble metals in acidic media, in which hydrogen production is easier and faster. Here, we report a water oxidation catalyst based on earth-abundant metals that performs well in acidic conditions. Specifically, we report the enhanced catalytic activity of insoluble salts of polyoxometalates with caesium or barium counter-cations for oxygen evolution. In particular, the barium salt of a cobalt-phosphotungstate polyanion outperforms the state-of-the-art IrO₂ catalyst even at pH < 1, with an overpotential of 189 mV at 1 mA cm^–2. In addition, we find that a carbon-paste conducting support with a hydrocarbon binder can improve the stability of metal-oxide catalysts in acidic media by providing a hydrophobic environment.

水分解是有效且经济地生产可再生燃料的一种有前途的方法，但是水氧化仍然是其技术发展的瓶颈，因为水氧化主要依赖于贵金属催化剂。尽管廉价的过渡金属氧化物在碱性介质中是竞争性水氧化催化剂，但它们无法与酸性介质中的贵金属竞争，在酸性介质中，氢的产生更容易，更快。在这里，我们报告了一种基于土壤丰富的金属的水氧化催化剂，该催化剂在酸性条件下表现良好。具体而言，我们报告了具有铯或钡抗衡阳离子的多金属氧酸盐的不溶性盐增强的催化活性，以促进氧气的释放。特别是钴-磷钨酸盐聚阴离子钡盐的性能优于最新的IrO ₂即使在pH <1的条件下也可以使用该催化剂，在1 mA cm ^–2时过电势为189 mV 。另外，我们发现具有烃类粘合剂的碳糊导电载体可以通过提供疏水性环境来改善金属氧化物催化剂在酸性介质中的稳定性。