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Defect engineering to activate the basal planes of transition metal dichalcogenides (TMDs) is critical for the development of TMD-based electrocatalysts as the chemical inertness of basal planes restrict their potential applications in hydrogen evolution reaction (HER). Here, we report the synthesis and evaluation of few-layer (7x7)-PtTe2-x with an ordered, well-defined and high-density Te vacancy superlattice. Compared with pristine PtTe2, (2x2)-PtTe2-x and Pt(111), (7x7)-PtTe2-x exhibits superior HER activities in both acidic and alkaline electrolytes due to its rich structures of undercoordinated Pt sites. Furthermore, the (7x7)-PtTe2-x sample features outstanding catalytic stability even compared to the state-of-the-art Pt/C catalyst. Theoretical calculations reveal that the interactions between various undercoordinated Pt sites due to proximity effect can provide superior undercoordinated Pt sites for hydrogen adsorption and water dissociation. This work will enrich the understanding of the relationship between defect structures and electrocatalytic activities and provide a promising route to develop efficient Pt-based TMD electrocatalysts.

Additional file 1: Figure S1. Uncropped blots images displayed in the context.

Abstract Sulige gas field is the largest tight sand gas field in China. In order to boost gas production of individual wells and to maximize economic return, hydraulically fractured horizontal wells are widely applied in Sulige gas field in recent years. Influenced by special geologic condition and stimulation, the production performance of hydraulically-fractured horizontal wells in tight sand gas reservoir is obviously different from that of conventional gas wells, such as:? The dominant flow regime is linear flow rather than pseudo-radial flow and this flow regime may continue for several years;? The dynamic reserve, drainage area and productivity of producing wells vary with time quickly, especially in the early stage of production. By correctly identifying the percolation characteristics and production performance of hydraulically fractured horizontal wells in tight sand gas reservoir and combine with modern gas production analysis technology, 137multi-stage fractured horizontal wells in Sulige gas field have been analyzed. Then a prediction chart of estimated reserves and new method of dynamic deliverability evaluation for Sulige multi-stage fractured horizontal wells are established. With these chart and methods, by using early stage production data, the dynamic reserve, drainage area and deliverability of multi-stage fractured horizontal wells can be predicted effectively with elapsed production time. In this paper, ultimate recoverable reserves, drainage sizes, drainage lengths and drainage widths of 57 multi-stage fractured horizontal wells in Sulige gas field are estimated. The results show that, in Sulige gas field, the average ultimately dynamic reserves and drainage sizes of multi-stage fractured horizontal wells are 2.8to 3.4 times that of offset fractured vertical wells, and the average initial deliverability of multi-stage fractured horizontal wells is 4.0 to 5.0 times that of offset fractured vertical wells. Based on these data, the reasonable well spacing and gas flow rate of Sulige gas field are suggested.