The preparation of a highly active non-PT-based catalyst for alkaline hydrogen evolution reaction (HER) at ampere current density is of great significance but challenging for the electrolysis of water by a new anion exchange membrane (AEM). Based on this,Professor Huang Hongwen of Hunan University and Professor Hu Zheng of Nanjing University (co-corresponding author) and othersA nanocone-assembled Ru3Ni (Na-Ru3Ni) catalyst was reported to exhibit a low overpotential of 168 mV at a current density of 1000 mA cm-2 and a low overpotential of 26 at 100 mV5 s-1 turnaround frequency. In addition, the catalyst can operate stably at 1000 mA cm-2 for 2000 h in a 60 M AEM electrolyzer, showing the best overall performance reported.
Through DFT calculations, the authors investigated the role of enhanced local electric fields and concentrated K+ ions in regulating the energy barrier of the basic HER pathway, i.e., the Volmer step for hydrolysis and the Tafel step for H2 generation. A layer of water molecules without K+ (No K+) and 1 12 monolayers was constructed on the surface of Ru3Ni (0001), respectively, under the influence of **K+ cations. In addition, the authors simulated a negatively charged but K+ Ru3Ni(0001) surface in the layer of water molecules to illustrate the effect of the electric field.
Gibbs free energy (δg) plots of basic HER in three different models, showing the corresponding hydrolysis energy barriers (ΔGW) and hydrogen adsorption free energy (ΔGH*). The results show that ΔGW is much larger than ΔGH* in the three models, suggesting that the process of hydrolysis to generate H* is a rate-determining step. For water dissociation, interfacial hydration K+ ions play a leading role in promoting the process of water dissociation, thereby accelerating HER kinetics. Therefore, these results well support the fact that Na-RU3Ni greatly improves basic HER activity.
engineering a local potassium cation concentrated microenvironment toward ampere-level current density hydrogen evolution reaction. energy environ. sci.,, doi: 10.1039/d2ee02836k.