The development of earth-abundant, low-cost, highly active, and durable bifunctional catalysts competent for efficient electrochemical water-splitting is intensively demanding and of vital importance to realize high-purity hydrogen production. Herein, we report that 3D quasi-amorphous pompon-like Co-O and Co-Se hybrid films grown on copper foil (Co-O@Co-Se/Cu) can be electrochemically synthesized from a choline chloride and urea mixed deep eutectic solvent, denoted as Reline, via a facile one-step electrochemical deposition approach. Benefiting from the induction effect of Se, the obtained Co-O@Co-Se/Cu hybrid electrode exhibits strongly enhanced catalytic activity. The optimal Co-O@Co-Se/Cu sample shows good activity and excellent durability for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in an alkaline solution with low overpotentials of 85 mV for HER and 340 mV for OER, respectively to reach a catalytic current of 10 mA cm⁻². The Co-Se component within the hybrid films is gradually converted into Co-O species during the course of the OER, which are responsible for the good OER performance. In addition, when performed as bifunctional catalysts in a two-electrode configured electrolyzer, the Co-O@Co-Se/Cu couple displays a water-splitting current of 10 mA cm^-2 at 1.65 V with reasonable stability for long-term electrolysis over 100 h. This simple one-step electrochemical synthesis route operated in the Reline-based deep eutectic solvent is demonstrated as an efficient strategy to fabricate active non-noble-free electrocatalysts toward overall water splitting applications.

能够有效地进行电化学水分解的富含地球的，低成本，高活性和耐用的双功能催化剂的开发迫切需要，并且对于实现高纯度制氢至关重要。在此，我们报道了可以在氯化铜和尿素混合的深共熔溶剂中电化学合成在铜箔上生长的3D准非晶态绒球状Co-O和Co-Se杂化膜（Co-O @ Co-Se / Cu）通过简便的一步式电化学沉积方法表示为Reline。受益于Se的诱导作用，获得的Co-O @ Co-Se / Cu混合电极表现出大大增强的催化活性。⁻²。在OER过程中，杂化膜中的Co-Se组分逐渐转变为Co-O物种，这是OER性能良好的原因。另外，当在双电极配置的电解槽中作为双功能催化剂使用时，Co-O @ Co-Se / Cu对 在1.65 V时表现出10 mA cm ^-2的水分解电流，并具有长期电解的合理稳定性。超过100小时 在基于Reline的深共熔溶剂中操作的这一简单的一步式电化学合成路线已被证明是一种有效的策略，可用于制备活性的非贵金属电催化剂，以用于整个水分解应用。