To solve the challenges of renewable energy not only requires highly efficient photovoltaic (PV) technologies but also the development of earth-abundant but highly active electrocatalysts to enable the most efficient and sustainable production of energy using electrocatalytic or photoelectrochemical (PEC) water splitting. Two-dimensional (2D) layered MX2 (M = Mo, W; X = S, Se) materials are promising non-precious electrocatalysts for the hydrogen evolution reaction (HER), however, their catalytic performance had been limited and the factors that influence the intrinsic catalytic activity have yet been clearly elucidated. By controlling the nanostructures and structural polymorphs of MX2 materials, we have significantly enhanced their HER catalytic activity. Furthermore, we report two successful cases to further enhance the catalytic activity via synergistic modulation of several key factors. Two ideal platforms, including porous 1T-MoS2 nanosheets made by liquid-ammonia assisted exfoliation and partially-crystallized 1T-MoSe2 nanosheets made by direct hydrothermal synthesis, were utilized to elucidate the contributions from various factors to enhanced HER catalytic activities. We have utilized several physical techniques to isolate the individual factors influencing the catalytic activity. We show that phase usually serves the key role in determining the HER activity, while the contribution from vacancy defects further contributes to the activity. The synergistic effects of phase and disorder engineering thus result in outstanding HER electrocatalytic activity and performance of about 150 mV vs RHE for j = -10 mA cm-2 and a Tafel slope of 40-50 mV dec-1, which are about the best among pure MoX2 electrocatalysts.

Synergistic phase and disorder engineering in 1T-MX2 nanosheets to enhance the electrocatalytic activity for hydrogen evolution reaction

254th National Meeting (2017)

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