Low-cost, layered transition-metal dichalcogenides (MX₂) based on molybdenum and tungsten have attracted substantial interest as alternative catalysts for the hydrogen evolution reaction (HER). These materials have high intrinsic per-site HER activity; however, a significant challenge is the limited density of active sites, which are concentrated at the layer edges. Here we unravel electronic factors underlying catalytic activity on MX₂ surfaces, and leverage the understanding to report group-5 MX₂ (H-TaS₂ and H-NbS₂) electrocatalysts whose performance instead mainly derives from highly active basal-plane sites, as suggested by our first-principles calculations and performance comparisons with edge-active counterparts. Beyond high catalytic activity, they are found to exhibit an unusual ability to optimize their morphology for enhanced charge transfer and accessibility of active sites as the HER proceeds, offering a practical advantage for scalable processing. The catalysts reach 10 mA cm⁻² current density at an overpotential of ∼50–60 mV with a loading of 10–55 μg cm⁻², surpassing other reported MX₂ candidates without any performance-enhancing additives.

作为钼和钨的替代催化剂，基于钼和钨的低成本层状过渡金属二硫化氢（MX ₂）引起了人们的极大兴趣。这些材料具有很高的固有每站点HER活性。然而，一个巨大的挑战是集中在层边缘的活性位点的密度有限。在这里，我们将揭示MX ₂表面催化活性的潜在电子因素，并利用这一认识报告第5组MX ₂（H -TaS ₂和H -NbS ₂）电催化剂的性能反而是主要来自高活性基平面位点，正如我们的第一性原理计算以及与边缘活性对应物的性能比较所表明的那样。除了具有较高的催化活性外，还发现它们具有出色的能力，可随着HER的进行优化其形态以增强电荷转移和活性位点的可及性，从而为可扩展工艺提供了实用优势。催化剂在约50-60 mV的超电势下达到10 mA cm ^-2的电流密度，负载量为10-55μgcm ^-2，超过了其他报道的没有任何性能增强添加剂的MX ₂候选物。