One-step synthesis and enhanced electrocatalytic hydrogen evolution performance of interlayer- expanded molybdenum disulfide

Abstract

A simple one-step hydrothermal method to synthesize interlayer-expanded molybdenum disulfide microflowers (E-MoS2) by increasing the proportion of thiourea in the reactant was proposed. In the method, ammonium thiocyanate, the product of thiourea conversion in hydrothermal reaction, is embedded into the interlayer of MoS2 formed in situ to expand the layer spacing, which avoids the complex synthesis process of traditional E-MoS2 and the introduction of foreign species and templates. The E-MoS2 reveals a small Tafel slope of 68.5 mV/dec and a low overpotential of 285 mV at -10 mA/cm2, markedly lower than those of initial MoS2 counterpart (122.2 mV/dec and 588 mV, respectively), indicating its excellent hydrogen evolution performance. Compared with the original MoS2, the enhanced hydrogen evolution performance of E-MoS2 can be attributed to the following reasons: the expansion of interlayer spacing optimizes the electronic structure of MoS2, thereby improving its conductivity and reducing the hydrogen adsorption free energy; the in situ intercalation of ammonium thiocyanate inhibits the growth and reduces the size of microflowers during the synthesis process, thus exposing more active sites for E-MoS2. Therefore, the E-MoS2 is expected to be a promising non-noble metal electrocatalyst for hydrogen evolution reaction.

Keywords

• interlayer expansion
• mos2
• ammonium thiocyanate
• electrocatalytic hydrogen evolution