Yubiao Niu
Swansea University Bay Campus, UK
Title: Enhanced catalytic activity of MoS2 nanoclusters for the hydrogen evolution reaction by Ni-doping and sulfur-enrichment
Biography
Biography: Yubiao Niu
Abstract
The discovery of highly active and low-cost electrochemical catalysts is a crucial challenge for the development of efficient hydrogen technologies. Molybdenum disulfide (MoS2) is an earth-abundant material and considered a promising candidate for electrocatalytic applications such as the hydrogen evolution reaction (HER). DFT calculations have demonstrated that transition metal (Fe, Co, Ni) doping of MoS2 should increase the activity in the HER. Here we report a novel one-step strategy for the preparation of Ni-doped transition metal-MoS2-x hybrid clusters, based on dual-target magnetron sputtering and gas condensation. The structure and composition of the clusters are analyzed by aberration-corrected scanning transmission electron microscope (STEM) in high-angle annular dark field (HAADF) mode coupled with EDX. From the electrochemical measurements, the Ni-MoS2-x nanoclusters display a favourable 100 mV shift in the HER onset potential and an almost 3-fold increase in exchange current density compared with undoped MoS2 clusters. It is believed that sulfur atoms at the edge sites of the MoS2 layers make the main contribution to the HER catalytic activity. Thus we have also explored sulfur-enrichment of (mass-selected) MoS2-x clusters, via sulfur evaporation and cluster annealing under vacuum conditions. Sulfur addition leads to MoS2+x clusters with well-developed crystalline structure instead of poorly ordered layer structures, and significantly enhances the activity in the HER, with 200 mV shifts to lower HER onset potentials and more than a 30-fold increase in exchange current density.