Selenium-enriched RuSe₂ (Ru_xSe) nanocrystals as electrocatalysts for the HER in basic media have been synthesized via a facile hydrothermal method followed by a calcination process. The catalytic activity of the obtained Ru_xSe nanocrystals is greatly dependent on calcination temperatures. The nanocrystals obtained at 400 °C (Ru_xSe-400) demonstrate the highest HER activity with a low overpotential of 45 mV to deliver a current density of 10 mA cm⁻² and a small Tafel slope of 31.4 mV dec⁻¹. The enhanced catalytic HER performance of Ru_xSe-400 could be attributed to the excessive Se on the RuSe₂ nanocrystal surface. Density functional theory (DFT) calculations reveal that the excessive Se would lower the energy barrier for water dissociation and lessen the dependence on the Ru sites for OH* adsorption but have a negligible effect on hydrogen adsorption energy, leading to an accelerated HER process. Furthermore, the excessive Se on the nanocrystal surface further endows the catalyst with promoted charge-transfer kinetics, ensuring a more efficient catalytic reaction. The strategy herein for the design of highly efficient HER catalysts by engineering the separation of different intermediate (H* and OH*) adsorption sites is expected to be extended to other electrocatalysts for high-efficiency energy conversion.

中文翻译：

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RuSe2纳米晶体上过量的Se会加速水离解，从而促进电催化氢的释放反应

富硒的RuSe ₂（Ru _x Se）纳米晶体作为HER在碱性介质中的电催化剂，已经通过一种简便的水热法并随后进行煅烧工艺合成。所获得的Ru _x Se纳米晶体的催化活性在很大程度上取决于煅烧温度。在400°C（Ru _x Se-400）下获得的纳米晶体显示出最高的HER活性，具有45 mV的低过电势，可提供10 mA cm ^-2的电流密度和31.4 mV dec ^-1的小Tafel斜率。Ru _x Se-400的催化HER性能增强可能归因于RuSe ₂上过量的Se纳米晶体表面。密度泛函理论（DFT）计算表明，过量的硒会降低水离解的能垒，并减少对OH *吸附的Ru位的依赖性，但对氢吸附能的影响可忽略不计，从而导致HER过程加速。此外，纳米晶体表面上过量的Se进一步使催化剂具有增强的电荷转移动力学，从而确保了更有效的催化反应。通过工程分离不同的中间（H *和OH *）吸附位点来设计高效HER催化剂的策略在本文中有望被扩展到其他电催化剂中，以实现高效的能量转化。