Acidic oxygen evolution reaction is crucial for practical proton exchange membrane water splitting electrolysers, which have been hindered by the high catalytic overpotential and high loading of noble metal catalysts. Here we present a torsion-strained Ta_0.1Tm_0.1Ir_0.8O_2-δ nanocatalyst with numerous grain boundaries that exhibit a low overpotential of 198 mV at 10 mA cm⁻² towards oxygen evolution reaction in 0.5 M H₂SO₄. Microstructural analyses, X-ray absorption spectroscopy and theoretical calculations reveal that the synergistic effects between grain boundaries that result in torsion-strained Ir–O bonds and the doping induced ligand effect collectively tune the adsorption energy of oxygen intermediates, thus enhancing the catalytic activity. A proton exchange membrane electrolyser using a Ta_0.1Tm_0.1Ir_0.8O_2-δ nanocatalyst with a low mass loading of 0.2 mg cm⁻² can operate stably at 1.5 A cm⁻² for 500 hours with an estimated cost of US$1 per kilogram of H₂, which is much lower than the target (US$2 per kg of H₂) set by the US Department of Energy.

酸性析氧反应对于实际的质子交换膜水分解电解槽至关重要，但由于贵金属催化剂的高催化过电势和高负载量而阻碍了这一反应。在这里，我们提出了一种扭转应变的 Ta _0.1 Tm _0.1 Ir _0.8 O _{2- δ}纳米催化剂，其具有许多晶界，在 0.5 MH ₂ SO _{4中在 10 mA cm} ^-2下表现出 198 mV 的低过电势对析氧反应. 微观结构分析、X 射线吸收光谱和理论计算表明，晶界之间的协同效应导致扭转应变的 Ir-O 键和掺杂诱导的配体效应共同调节了氧中间体的吸附能，从而提高了催化活性。质子交换膜电解槽使用 Ta _0.1 Tm _0.1 Ir _0.8 O _{2- δ}纳米催化剂，低质量负载为 0.2 mg cm ^-2可以在 1.5 A cm ^{- 2}下稳定运行500 小时，估计成本为每公斤 1 美元H _{2 ，远低于目标（每公斤 H 2} 2 美元）) 由美国能源部制定。