Investigating the Hydrogen Evolution Reaction Mechanism of Ni₃Se₄ Nanoclusters Decorated on Ni₃N Surface via Ambient Pressure X-ray Photoelectron Spectroscopy

Dessalew Dagnew Alemayehu^1,3, Meng-Che Tsai^2,5, Meng-Hsuan Tsai³, Chueh-Cheng Yang³, Chun-Chi Chang^1,3, Chia-Yu Chang^1,3, Endalkachew Asefa Moges⁴, Keseven Lakshmanan⁴, Yosef Nikodimos⁴, Wei-Nien Su^1,5, Chia-Hsin Wang^3*, Bing Joe Hwang^3,4,5

¹Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei, Taiwan
²Department of Greenergy, National University of Tainan, Tainan, Taiwan
³Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu, Taiwan
⁴Department of Chemical Engineering, ational Taiwan University of Science and Technology, Taipei, Taiwan
⁵Sustainable Electrochemical Energy Development (SEED) Center, National Taiwan University of Science and Technology, Taipei, Taiwan

* Presenter:Chia-Hsin Wang, email:wang.ch@nsrrc.org.tw

Hydrogen fuel is regarded as one of the most promising alternatives to fossil fuels for addressing the global energy and environmental crisis. Among various approaches to hydrogen production, water electrolysis powered by renewable energy is considered the most sustainable. Therefore, the development of low-cost and highly efficient electrocatalysts for the water-splitting process is a critical research focus. A comprehensive understanding of the reaction mechanisms is essential to guide the rational design of advanced electrocatalysts. Ambient Pressure X-ray Photoelectron Spectroscopy (APXPS), in conjunction with an innovative electrochemical cell configuration, has emerged as a powerful technique for probing surface reaction mechanisms under near-ambient conditions. In this study, we report the development of a dual-site heterogeneous catalyst, Ni₃Se₄–Ni₃N, fabricated by decorating Ni₃Se₄ nanoclusters onto a Ni₃N substrate. The optimized catalyst exhibited outstanding hydrogen evolution reaction (HER) activity, requiring an overpotential of only ~60 mV to achieve a current density of 10 mA/ cm², and demonstrated excellent stability under higher cathodic potentials. APXPS measurements conducted from ultra-high vacuum (UHV) to a water vapor pressure of 0.5 mbar revealed that the Ni₃Se₄–Ni₃N catalyst possesses significantly enhanced water adsorption and dissociation capabilities compared to individual Ni₃N and Ni₃Se₄ catalysts. Furthermore, in-situ APXPS during electrochemical operation revealed a marked increase in the N 1s signal associated with N–H bonding as the cathodic potential increased. Simultaneously, the Se 3d spectra exhibited a slight negative shift, and the intensity of the SeOx component diminished at more negative potentials. These findings suggest that surface-adsorbed hydrogen atoms were transferred to adjacent electron-rich selenide sites, where molecular hydrogen is formed and subsequently released via a hydrogen spillover mechanism. This dual-site synergy offers valuable insights into the rational design of efficient HER electrocatalysts. (This result has already been published in JACS, 2025, 147, 16047.)

Keywords: APXPS, electrocatalysts, HER