Lixiong Xu,Yifan Yang,Chenyue Li,Rongqian Ning,Jun Ma,Mengqin Yao,Shuo Geng,Fei Liu
The electrocatalytic glycerol oxidation reaction (GOR) is an efficient way to reduce the overpotential of the anodic reaction of electrocatalytic water splitting with abundant high-value byproducts. However, it has always been difficult to reveal a clear reaction path and real active site during the electrocatalytic glycerol oxidation reaction (GOR) process. In this work, NiOOH/Ni 3 S 2 /NF, a model catalyst was synthesized by the two-step method, and the reaction path of the electrocatalytic oxidation of glycerol on NiOOH/Ni 3 S 2 /NF was clearly unveiled by the in situ infrared and Raman analysis. In addition, the TEM after GOR and in-situ Raman intuitively demonstrated that the NiOOH was the real active site during the GOR process. Consequently, the synthesized NiOOH/Ni 3 S 2 /NF catalyst achieved a current density of 10 mA cm −2 at 1.227 V vs . RHE and obtained a high formic acid Faraday efficiency of 97.7 % at a low potential of 1.4 V vs . RHE. This work demonstrates an effective method for unveiling the GOR mechanism and the other relevant electrocatalytic reaction processes.
Zhong Wu,Yanhui Feng,Zhenbo Qin,Xiaopeng Han,Xuerong Zheng,Yida Deng,Wenbin Hu
Development of efficient non-noble metal catalysts for water splitting is of great significance but challenging due to the sluggish kinetics of the hydrogen evolution reaction (HER) in alkaline medium. Herein, a bimetallic multi-level layered catalytic electrode composed of Ni 3 S 2 nanosheets with secondary Co-NiOOH layer of 3D porous and free-standing cathode in alkaline medium is reported. This integrated synergistic catalytic electrode exhibits excellent HER electrocatalytic performance. The resultant Ni 0.67 Co 0.33 /Ni 3 S 2 @NF electrode displays the highest HER activity with only overpotentials of 87 and 203 mV to afford current densities of 10 and 100 mA·cm −2 , respectively, and its Tafel slope is 80 mV·dec −1 . The chronopotentiometry operated at high current density of 50 mA·cm −2 shows negligible deterioration, indicating better stability of Ni 0.67 Co 0.33 /Ni 3 S 2 @NF electrode than Pt/C (20 wt.%). Such a desirable catalytic performance is attributed to the modification of physical and electronic structure that exposes abundant active sites and improves the intrinsic catalytic activity toward HER, which is also confirmed by electrochemically active surface area and X-ray photoelectron spectroscopy analysis. This work provides a strong support for the rational design of high-performance bimetallic electrodes for industrial water splitting.
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