Doping of MoS by "Cu" and "V": An Efficient Strategy for the Enhancement of Hydrogen Evolution Activity.

To replace Pt-based compounds in the electrocatalytic hydrogen evolution reaction (HER), MoS has already been established as an efficient catalyst. The electrocatalytic activity of MoS is further improved by tuning the morphology and the electronic structure through doping, which helps the band energy position to be modified. Presently, thin sheets of MoS (MoS-TSs) are synthesized via a microwave technique. Thin sheets of MoS can outperform nanosheets of MoS in the HER. Further, the efficiency of the thin sheets is improved by doping with different metals like Cu, V, Zn, Mn, Fe, Sn, etc. "Cu"- and "V"-doped MoS-TSs are highly efficient for the HER. At a fixed potential of -0.588 V vs RHE, Cu-doped MoS (Cu-MoS-TS), V-doped MoS (V-MoS-TS), and MoS-TS can generate current densities of 327.46, 308.45, and 127.82 mA/cm, respectively. The electrochemically active surface area increases nearly 7.7-fold and 2.5-fold for Cu-MoS-TS and V-MoS-TS than for MoS-TS, respectively. Cu-MoS-TS shows exceptionally high electrocatalytic stability up to 140 h in an acidic medium (0.5 M HSO). First-principles calculations using density functional theory (DFT) are performed, which are well matched with the experimental observations. DFT calculations dictate that after doping with "V" and "Cu" both valance band maxima and conduction band minima are uplifted, which indicates the higher hydrogen-ion-reducing ability of M-MoS-TS (M = Cu, V) compared to bare MoS-TS.