Metallic PtC monolayer as a promising hydrogen evolution electrocatalyst†

Reasonable design of hydrogen evolution reaction (HER) electrocatalysts with low Pt loading and excellent catalytic performance is a key challenge in finding efficient and cost attractive catalysts. Pt with its unique d-electrons provides new opportunities for the development of HER catalysts when it forms compounds with highly earth-abundant C. Herein, we focused on designing highly efficient catalysts composed of Pt and C elements using first-principles structure search simulations, identifying four stability PtC_x monolayers. The novel PtC monolayer with a zigzag C chain not only possesses lower Pt loading but also shows inherent metallicity. Meanwhile, its H₂O adsorption and dissociation abilities are efficient and facile. The HER activity of the PtC monolayer is comparable to that of commercial Pt, with desirable ΔG_H* values and larger exchange current density, which are mainly attributed to lower charge donation of Pt, larger occupation of Pt PDOS at the Fermi level, and paired electrons of the zigzag C chain. Moreover, its excellent HER activity can be maintained even at high H coverage under strain and solvent effect. All these attractive properties render the PtC monolayer an appropriate HER catalyst.