Modulation rate on adsorption and catalysis of 2D Pt: the effects of adsorbate-induced surface stress

Recently, it has been reported for ultrathin 2D metals that positive surface stress of a clean surface (τ1) can induce considerable compressive lattice strain towards optimized adsorption energy and catalytic properties (L. Wang et al., Science, 2019, 363, 870). We report negative surface stress (τ2) induced by adsorbates at finite coverage counteracting the effects of τ1, by studying the hydrogen adsorption properties and hydrogen evolution reaction (HER) catalysis performance of 2D Pt. Due to the competition between τ1 and τ2, the resultant lattice strain of 2D Pt is small. Consequently, modulation speed in adsorption energy and Tafel reaction barriers is significantly reduced as the Pt slab thickness decreases. Our study highlights the importance of properly including the effects of τ2 in predicting and understanding the catalytic properties of 2D metals when coverage of adsorbates is high.