Chakraborty Soumita, Marappa Shivanna, Agarwal Sakshi, Bagchi Debabrata, Rao Ankit, Vinod Chathakudath P, Peter Sebastian C, Singh Abhishek, Eswaramoorthy Muthusamy
Chemistry and Physics of Materials Unit, School of Advanced Materials (SAMat), JNCASR, Bengaluru 560064, India.
Materials Research Centre, IISc, Bengaluru, Karnataka 560012, India.
ACS Appl Mater Interfaces. 2022 Jul 20;14(28):31951-31961. doi: 10.1021/acsami.2c06210. Epub 2022 Jul 7.
NiFe layered double hydroxide (NiFe LDH) grown in the presence of MoS (rich in 1T phase) shows exceptional performance metrics for alkaline oxygen evolution reaction (OER) in this class of composites. The as-prepared NiFe LDH/MoS composite (abbreviated as MNF) exhibits a low overpotential (η) of 190 mV; a low Tafel slope of 31 mV dec; and more importantly, a high stability in its performance manifested by the delivery of current output for 45 h. It is important to note that this could be achieved with an exceedingly low loading of 0.14 mg cm. The mass activity of this composite (97 A g) is about 14 times greater than that of the conventional RuO (7 A g) at η = 200 mV. When normalized with respect to the total metal content, a mass activity of 1000 A g (η = 300 mV) was achieved. Impedance analysis further reveals that the significant reduction in charge-transfer resistance and hence high current density (5 times greater as compared to NiFe LDH at η = 300 mV) observed for MNF is associated with interfacial adsorption kinetics of intermediates (). Significant enhancement in the intrinsic activity of MNF over LDH has been observed through normalization of current with the electrochemically active surface area. Computational studies suggest that the Ni centers in the composite act as the active sites for OER, which is well-corroborated with the observed postreaction appearance of Ni species.
在富含1T相的MoS存在下生长的镍铁层状双氢氧化物（NiFe LDH）在这类复合材料的碱性析氧反应（OER）中表现出优异的性能指标。所制备的NiFe LDH/MoS复合材料（简称为MNF）表现出190 mV的低过电位（η）；31 mV dec的低塔菲尔斜率；更重要的是，其性能具有高稳定性，在45小时的电流输出中得到体现。需要注意的是，这可以通过0.14 mg cm的极低负载量实现。在η = 200 mV时，该复合材料的质量活性（97 A g）约为传统RuO（7 A g）的14倍。当相对于总金属含量进行归一化时，实现了1000 A g（η = 300 mV）的质量活性。阻抗分析进一步表明，MNF观察到的电荷转移电阻显著降低以及因此在η = 300 mV时的高电流密度（与NiFe LDH相比大5倍）与中间体的界面吸附动力学有关。通过将电流与电化学活性表面积进行归一化，观察到MNF相对于LDH的本征活性有显著增强。计算研究表明，复合材料中的Ni中心作为OER的活性位点，这与反应后观察到的Ni物种外观得到了很好的证实。
