Proton exchange membrane (PEM) water electrolysers promise efficient production of high-purity hydrogen. Moreover, due to their rapid dynamic responsiveness, they are also ideal for coupling to renewable power sources. However, the acidic nature of the reaction environment in a PEM electrolyser causes corrosion in many materials and has limited the choice of catalyst used at the anode (where O₂ is generated) largely to those based on iridium, a rare and expensive metal. For example, while cobalt-based oxides have been suggested to have activity approaching iridium, their stability is typically poor due to cobalt ion dissolution. Now, F. Pelayo García de Arquer and colleagues in Spain, France and the UK report an iridium-free, delaminated cobalt tungstate catalyst that can operate in an 80 °C PEM electrolyser for 608 h at a current density of 1 A cm^–2.

The researchers synthesize CoWO₄ hydrothermally, before dispersing it in 0.1 M KOH; this treatment leads to a delaminated, flake-like structure with a large number of vacancies due to leaching of WO₄^2– anions. The team find that the delaminated material contains a high density of trapped water and hydroxide groups, which — in contrast to Co₃O₄ — makes the dissolution of cobalt ions thermodynamically unfavourable. This durability is reflected in the strong stability observed in both standard two-compartment electrochemical cell tests and PEM electrolyser runs. The activity of the catalyst is also notable, with the researchers recording a current density of 1.8 A cm^–2 at 2 V in the PEM electrolyser.

质子交换膜 (PEM) 水电解槽有望高效生产高纯度氢气。此外，由于其快速的动态响应能力，它们也是耦合可再生能源的理想选择。然而，PEM 电解槽中反应环境的酸性性质会导致许多材料腐蚀，并限制了阳极（生成 O ₂ ）所用催化剂的选择，主要是基于铱的催化剂，稀有且昂贵的金属。例如，虽然钴基氧化物被认为具有接近铱的活性，但由于钴离子溶解，它们的稳定性通常很差。现在，F. Pelayo García de Arquer 及其西班牙、法国和英国的同事报告了一种无铱、分层钨酸钴催化剂，可以在 80 °C PEM 电解槽中以 1 A cm ^–2 。

研究人员通过水热法合成了 CoWO ₄ ，然后将其分散在 0.1 M KOH 中；由于 WO ₄ ^2– 阴离子的浸出，这种处理导致分层、片状结构，并具有大量空位。研究小组发现，分层材料含有高密度的截留水和羟基，与 Co ₃ O ₄ 相比，这使得钴离子的溶解在热力学上不利。这种耐用性体现在标准两室电化学电池测试和 PEM 电解槽运行中观察到的强大稳定性。该催化剂的活性也很引人注目，研究人员在 PEM 电解槽中记录到 2V 电压下的电流密度为 1.8 A cm ^–2 。