The excellent catalytic activity of metallic MoS₂ edges for the hydrogen evolution reaction (HER) has led to substantial efforts towards increasing the edge concentration. The 2H basal plane is less active for the HER because it is less conducting and therefore possesses less efficient charge transfer kinetics. Here we show that the activity of the 2H basal planes of monolayer MoS₂ nanosheets can be made comparable to state-of-the-art catalytic properties of metallic edges and the 1T phase by improving the electrical coupling between the substrate and the catalyst so that electron injection from the electrode and transport to the catalyst active site is facilitated. Phase-engineered low-resistance contacts on monolayer 2H-phase MoS₂ basal plane lead to higher efficiency of charge injection in the nanosheets so that its intrinsic activity towards the HER can be measured. We demonstrate that onset potentials and Tafel slopes of ~−0.1 V and ~50 mV per decade can be achieved from 2H-phase catalysts where only the basal plane is exposed. We show that efficient charge injection and the presence of naturally occurring sulfur vacancies are responsible for the observed increase in catalytic activity of the 2H basal plane. Our results provide new insights into the role of contact resistance and charge transport on the performance of two-dimensional MoS₂ nanosheet catalysts for the HER.

Nature Materials (2016) doi:10.1038/nmat4660
Received 21 January 2016 Accepted 03 May 2016 Published online 13 June 2016

http://www.nature.com/nmat/journal/vaop/ncurrent/full/nmat4660.html

MoS₂边界上极好的电催化析氢性能已经促使研究人员想方设法增加边界浓度。2H基面的导电性较差导致电荷转移不够有效，影响了其电催化析氢性能。最近，美国的科学家研究发现：通过基底与MoS₂纳米片的电子耦合，单层MoS₂纳米片的2H基面能够表现出与目前金属边界和1T相MoS₂相比拟的电催化析氢性能。起始电位和塔菲尔斜率分别为0.1V和50mV/dec。有效的电荷注入和硫空位的出现对于催化性能的提高起到了主要作用。（Nature Materials DOI: 10.1038/NMAT4660）（新材料在线）