2D Metal-Free BSi<sub>5</sub> with an Intrinsic Metallicity and Remarkable HER Activity
Wenyuan Zhang, Huan Lou, Guochun Yang
Abstract
One of the most urgent and attractive topics in electrocatalytic water splitting is the exploration of high-performance and low-cost catalysts. Herein, we have proposed three fresh two-dimensional nanostructures (BSi 5, BSi 4, and BSi 3 ) with inherent metallicity contributed by delocalized π electrons based on first-principles calculations. Their planar atoms arrangement, akin to graphene, is in favor of the availability of active atoms and H adsorption/deadsorption. Among them, the BSi 5 monolayer shows the best HER activity, even superior to a commercial Pt catalyst. Moreover, its extraordinary HER activity can be maintained under high H coverage and large biaxial strain, mainly originating from the fact that B 2p z orbital electrons are responsible for the B–H interaction. Further analysis reveals that there appears to be a linear correlation between the magnitude of B 2p z DOS at the Fermi level and Gibbs free energy in both three proposed nanostructures and five hypothetical B–Si nanostructures. Our work represents a significant step forward toward the design of metal-free HER catalysts.