碳布负载的钴镍双金属沸石咪唑框架作为独立电极用于高效电催化析氧反应

Co-Ni Bimetallic Zeolitic Imidazolate Frameworks Supported on Carbon Cloth as Free-Standing Electrode for Highly Efficient Oxygen Evolution

开发低成本、高效和稳定的电催化剂对于加快水分解中的析氧反应(OER)速率,实现可再生、清洁和大规模能源转换技术至关重要。在本文中,我们开发了一种简单的方法来制备钴镍双金属沸石咪唑框架(CoNi-ZIF),通过低温热解去除客体分子将CoNi-ZIF纳米片牢固地负载到碳布(CoNi-ZIF-CC-200)上。组装的独立电极避免了对粘合剂的依赖和无效表面积的增加,从而显著提高了催化剂的催化活性和传质效率。电化学测试结果表明CoNi-ZIF-CC-200独立电极在OER过程中表现出良好的电化学活性和稳定性。CoNi-ZIF-CC-200独立电极在10 mA·cm^(-2)下表现出255 mV的低过电位,并且在恒电位测量过程中保持10 h以上的稳定运行。此外,由CoNi-ZIF-CC-200独立电极作为阳极和Pt/C作为阴极组成的水分解系统表现出优异的稳定性。

In recent years,hydrogen production has driving a growing focus in the researches of clean energy,particularly the significance of the oxygen evolution reaction(OER)in water splitting.However,the most fascinating OER catalysts of noble metals are hindered by high cost,limited resources,and poor stability.Therefore,the development of low-cost,efficient,stable,and replaceable electrocatalysts is of utmost importance to accelerate the rate of OER in water splitting and realizing renewable,clean,and large-scale energy conversion technologies.Bimetallic and polymetallic electrocatalysts have shown enormous potential,as each metal component can independently or synergistically enhance the electrocatalytic activity.However,during the catalytic process,some metal ions may leach,leading to changes in the catalyst surface morphology and a significant reduction in activity and stability.Extensive research efforts are being devoted to effectively address the challenges associated with metal dissolution.In this study,we have developed a simple method for preparing bimetallic CoNi zeolitic imidazolate framework(CoNi-ZIF)by removing guest molecules through low-temperature pyrolysis and firmly loading CoNi-ZIF nanosheets onto carbon cloth(CoNi-ZIF-CC-200).The resulting free-standing electrodes have several advantages,including independence from adhesives and avoidance of ineffective surface area,thereby significantly improving the catalytic activity and mass transfer efficiency of the catalyst.The electrochemical test results indicate that the CoNi-ZIF-CC-200 free-standing electrode exhibits good electrochemical activity and stability during the OER process.Specifically,the CoNi-ZIF-CC-200 electrode demonstrates a low overpotential of 255 mV under a current density of 10 mA·cm^(-2) and maintains stable operation for over 10 h during potentiostatic measurements.Additionally,the water splitting system consisting of the CoNi-ZIF-CC-200 free-standing electrode as the anode and Pt/C as the cathode exhibits excellent stability.The research highlights the use of a low-temperature pyrolysis strategy for firmly loading bimetallic ZIF-L nanosheets onto carbon cloth.This approach results in well-arranged nanosheet arrays,which prevent ineffective surface area and improve mass transfer efficiency during the OER process.Moreover,the removal of guest molecules at low temperatures leads to the formation of Co/Ni oxides,which play a crucial role in catalyzing the OER.The prepared free-standing electrode based on bimetallic ZIF and oxide demonstrates excellent electrochemical activity and stability in both three-electrode and two-electrode water splitting systems using 1 mol·L-1 KOH as the electrolyte.It is strongly believed that CoNi-ZIF-CC-200 holds great promise for future applications in large-scale electrocatalytic hydrogen production systems.