Co doped MoS2 as Bifunctional Electrocatalyst for Hydrogen Evolution and Oxygen Reduction Reactions

Pure MoS2 and MoS2 compounds were doped with Co using a hydrothermal method. XRD results indicate that two of the five diffraction peak results at 9.2 degrees and 18.2 degrees may be attributed to low crystallinity of MoS2. The (002) diffraction peaks for the Co-doped MoS2 shifted to smaller angle, which may be due to the Mo4+ ions (r = 0.65 angstrom) having been replaced by larger Co2+ ions (r = 0.74 angstrom). Raman results show that the intensity of the A(1g) mode was greater than that of the E-2g(1) mode for our samples; this indicates that the samples have edge-terminated structures and possess more electrocatalytic active sites. The results of XPS also confirm that the cobalt ions substituted molybdenum atoms into the lattice of MoS2. Results from the electrocatalytic test confirms that cobalt doping reduces the charge transfer resistance and increases the electrocatalytic active sites, which are conducive to improving its electrocatalytic performance.