Defect engineered Janus MoSiGeN4 as highly efficient electrocatalyst for hydrogen evolution reaction

It is well known that defect engineering is very important to the improvement of catalyst activity. In this paper, defect engineering is introduced into Janus MoSiGeN4 to regulate hydrogen evolution reaction (HER) activity. Based on density functional theory, a theoretical study is carried out to clarify the roles of vacancy and transition metal (TM) atom doping in Janus MoSiGeN4. Five different vacancies are considered, and results suggest that outmost N vacancy can effectively enhance the HER activities. For VN2@MoSiGeN4 and VN1@MoSiGeN4 struc-tures, the hydrogen adsorption Gibbs free energy (Delta GH*) is 0.015 eV and 0.145 eV, respectively. Moreover, a systematic screening of eleven non-precious TM atoms (V, Cr, Mn, Fe, Co, Ni, Cu, Nb, Mo, Ta and W) doped MoSiGeN4 as HER catalysts reveals that Fe-, Mn-, and Nb-doped MoSiGeN4 show better HER activity than that of Pt with the Delta GH* of 0.013 eV, 0.061 eV, and 0.087 eV, respectively. Electronic properties, electron charge density difference and Bader charge are employed to explore the origin of electrocatalytic activity. Our study confirms that vacancy and TM atom doping are effective means to enhance electrocatalytic performance and defect engineered Janus MoSiGeN4 can be served as highly efficient HER catalyst.