Comparison of liquid exfoliated transition metal dichalcogenides reveals MoSe2 to be the most effective hydrogen evolution catalyst
By Gholamvand, Zahra and McAteer, David and Backes, Claudia and McEvoy, Niall and Harvey, Andrew and Berner, Nina C. and Hanlon, Damien and Bradley, Conor and Godwin, Ian and Rovetta, Aurlie and Lyons, Michael E. G. and Duesberg, Georg S. and Coleman, Jonathan N.
Published in Nanoscale
The Royal Society of Chemistry
2016
Abstract
While 2D transition metal dichalcogenides are known to be promising materials for electrocatalysis of hydrogen production, it is not clear which member of this family of materials is the most effective catalyst. Here we perform a comprehensive study, comparing the catalytic performance of electrodes consisting of porous arrays of liquid exfoliated MX2 nanosheets (M = Mo, W; X = S, Se, Te). We find a clear hierarchy with selenides > sulphides > tellurides with MoSe2 clearly out-performing the other materials. In all cases the performance, as characterised by current density at a given potential, can be improved by increasing the number of active sites (via control of the electrode thickness) and/or by adding carbon nanotubes to the electrode (i.e. increasing the electrode conductivity). While all materials formed reasonably stable electrodes, addition of nanotubes tended to improve mechanical cohesion. In an attempt to maximise performance, we prepared thick ([similar]15 [small mu ]m), free standing MoSe2/SWNT composite electrodes which displayed Tafel slopes of [similar]77 mV per decade and exchange current densities of [similar]0.1 mA cm-2. These electrodes had low onset potentials, reaching -2 mA cm-2 at -41 mV (vs. RHE) and generated high current densities of -35 mA cm-2 at -200 mV (vs. RHE).