Li Zhihui, Zhang Xinyu, Teng Yiran, Zhang Hanming, Xu Tongguang, Teng Fei
Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology (CICAEET), Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control (AEMPC), Jiangsu Engineering and Technology Research Center of Environmental Cleaning Materials (ECM), Joint International Research Laboratory of Climate and Environment Change (ILCEC), School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, 219 Ningliu Road, Nanjing 210044, China.
Nanjing Software Research Institute of China United Network Communications Co., Ltd, 230 Lushan Road, Nanjing 210004, China.
ACS Appl Mater Interfaces. 2024 Nov 13;16(45):61921-61933. doi: 10.1021/acsami.4c11560. Epub 2024 Oct 30.
The high cost of hydrogen production by water electrolysis severely challenges its commercial application. It is highly desirable to develop efficient electrocatalysts and innovative electrolytic cells. Introducing additional metal nodes to form bimetallic metal-organic framework (MOF) is a simple, feasible strategy to overcome the poor electrocatalytic performance of single-metal MOF. In this study, the hydrothermal method is used to synthesize bimetallic NiCo-BTC. It is found that for hydrogen evolution reaction (HER), NiCo-BTC merely requires a potential of -0.203 V (vs reverse hydrogen electrode, RHE) to achieve 10 mA cm, which is significantly lower than that of Ni-BTC (-0.341 V vs RHE). Notably, electrochemical impedance spectroscopy (EIS) and distribution of relaxation time (DRT) analysis indicate that NiCo-BTC has improved charge transfer and mass transfer process, compared with Ni-BTC. Electron paramagnetic resonance (EPR) confirms that NiCo-BTC has more unpaired electrons than Ni-BTC. Density functional theory (DFT) calculations show that compared with Ni-BTC, NiCo-BTC is more thermodynamically favorable for the adsorption of H, OH, and HO. It demonstrates that the change of mass transfer caused by bimetallic nodes and the delicate variation of MOF surface play an important role in the electrochemical process. Moreover, a novel electrolytic cell was developed using a methanol oxidation reaction (MOR) to replace oxygen evolution reaction (OER). In this MOR-based electrolytic cell, a current density of 50 mA cm can be achieved at only a cell voltage of 1.85 V, which is lower than the 2.22 V of OER-based electrolytic cell, suggesting that 16.7% electric energy can be saved. At the same time, the Faraday efficiency (FE, 98.2%) of the MOR-based cell is higher than that (94.5%) of the OER-based cell. This research offers a promising strategy for low-cost hydrogen production.
通过水电解制氢的高成本严重挑战了其商业应用。开发高效的电催化剂和创新的电解槽非常必要。引入额外的金属节点以形成双金属金属有机框架（MOF）是克服单金属MOF电催化性能差的一种简单可行的策略。在本研究中，采用水热法合成了双金属NiCo-BTC。研究发现，对于析氢反应（HER），NiCo-BTC仅需-0.203 V（相对于可逆氢电极，RHE）的电位即可达到10 mA cm，这明显低于Ni-BTC（-0.341 V vs RHE）。值得注意的是，电化学阻抗谱（EIS）和弛豫时间分布（DRT）分析表明，与Ni-BTC相比，NiCo-BTC的电荷转移和传质过程得到了改善。电子顺磁共振（EPR）证实，NiCo-BTC比Ni-BTC具有更多的未成对电子。密度泛函理论（DFT）计算表明，与Ni-BTC相比，NiCo-BTC在热力学上更有利于H、OH和HO的吸附。这表明双金属节点引起的传质变化和MOF表面的微妙变化在电化学过程中起着重要作用。此外，开发了一种新型电解槽，使用甲醇氧化反应（MOR）代替析氧反应（OER）。在这种基于MOR的电解槽中，仅在1.85 V的电池电压下就能实现50 mA cm的电流密度，这低于基于OER的电解槽的2.22 V，表明可以节省16.7%的电能。同时，基于MOR的电解槽的法拉第效率（FE，98.2%）高于基于OER的电解槽（94.5%）。这项研究为低成本制氢提供了一种有前景的策略。
