Zegao Wang, a distinguished research fellow of SCU College of Materials Science and Engineering has made significant headway in a joint research with Professor Xiao Cheng Zeng of the University of Nebraska-Lincoln. The research findings are published under the title “ Reversing Interfacial Catalysis of Ambipolar WSe2 Single Crystal ” in Advanced Science ( IF=15.804 ). Sichuan University is the first work unit of this paper.

Hydrogen is a green energy carrier due to its high energy density, safety and pollution-free production. The splitting of water by electrocatalysts isconsidereda safe and controllable way to prepare hydrogen. By electrolyzing water, electric energy can be converted into hydrogen energy for storage, so it is deemed a form of electric energy storage. “ The key to realizing this reaction is to find an efficient and robust electrocatalyst which can effectively lower the reaction barrier and result in highly efficient utilization of electric. ”  ( Introduction ) However, the catalytic mechanism is very complex due to factors, such as material composition, microstructure and so on.

Zegao Wang published a paper in NPG Asia Materials ( 2018, 10, 703-712. ), in which he systematically revealed the bipolar electric transport characteristics of tungsten selenide field modulation ( the carrier can be converted between n-type and p-type due to the regulation of external electric field ). On the foundation of his previous findings, Zegao Wang has made new discoveries:  The effect of the electron carrier, hole carrier, and conductance in catalysis reaction has been carefully discussed. The results show that with the similar conductance, WSe₂ with the electrons as the dominant carrier shows much higher catalytic activity than that with the holes as the dominant carrier. With increasing the gate voltage in electron dominated WSe₂, the catalytic activity can be further enhanced with the Tafel slope decreasing from 138 to 104 mV per decade, attributing to the increased electron concentration rather than the conductance. Furthermore, the Gibbs free energies of adsorbed atomic hydrogen on WSe₂with different electron and hole area concentrations are calculated.--- The results show that the electron carrier plays a more important role in HER, rather than the conductance, which provides a new strategy to rationally design highly efficient electrocatalysts.” ( Conclusion ) The research in this paper provides a new idea for further optimizing the design of high efficiency catalyst.

Figure 1. The electrocatalytic performance in electron and hole branches on the ambipolar WSe₂device.

Zegao Wang is a distinguished research fellow of SCU College of Materials Science and Engineering. His research is mainly focused on electronic functional materials and electronic components. With an H-index of 30, Zegao Wang has published more than 110 SCI papers in Advanced Materials, Science Advances, PNAS and other journals.

Article link: https://onlinelibrary.wiley.com/doi/10.1002/advs.201901382