Abstract:

Hydrogen energy is considered as one of the most effective energy vectors to achieve carbon neutrality due to its high calorific value and clean, pollution-free characteristics. Electrolysis of water is an effective way to achieve sustainable hydrogen production. Among them, the slow kinetics of the oxygen evolution reaction (OER) leads to low water decomposition efficiency, and it is urgent to develop efficient and stable electrocatalysts. Herein, we utilize the coordination interaction between polyhydric alcohols, urea, and CoCl₂·6H₂O to form supramolecular ternary deep eutectic solvent (DES) systems. By employing a one-pot solvothermal method, surface-roughened two-dimensional CoCO₃ nanosheets were constructed to enhance electrocatalytic OER efficiency. The impact of the number of alcohol hydroxyl groups on the morphology and performance of CoCO₃ was studied. The research shows that the CoCO₃-Gly catalyst prepared by using a ternary DES system of glycerol, urea, and CoCl₂·6H₂O exhibits a more fluffy, thinner, and rougher sheet-like structure. The catalyst exhibits superior OER performance, with an overpotential of 311 mV at a current density of 10 mA·cm^-2 and a current retention rate of 99% after 24 h of stability testing.

Key words: deep eutectic solvents, cobalt carbonate, catalyst, electrocatalysis, oxygen evolution reaction, polyhydric alcohols

摘要：

氢能因其热值高、清洁无污染等优势，被认为是实现碳中和最有效的能源载体之一。电解水制氢是实现可持续制氢的有效途径。其中，析氧反应（OER）缓慢动力学过程导致水分解效率低下，迫切需要开发高效、稳定的电催化剂。利用多元醇、尿素与CoCl₂·6H₂O之间的配位作用形成超分子三元低共熔溶剂（DES）体系，通过一锅溶剂热法构建表面粗糙的二维CoCO₃纳米片，用于提升电催化OER效率，并针对醇羟基数量对CoCO₃形貌及性能影响进行了探究。研究表明，丙三醇、尿素和CoCl₂·6H₂O三元DES体系制备的CoCO₃-Gly催化剂，呈现更蓬松、更薄、更粗糙的片状结构，具有更加优异的OER性能，电流密度在10 mA·cm^-2时过电位311 mV，经24 h稳定性测试电流保留率达99%。

关键词: 低共熔溶剂, 碳酸钴, 催化剂, 电催化, 析氧反应, 多元醇