Layered Nanocomposites of Polymer-Functionalized Reduced Graphene Oxide and Borocarbonitride with MoS₂ and MoSe₂ and Their Hydrogen Evolution Reaction Activity

Nanocomposites formed by poly­(diallyldimethylammonium chloride) (PDDA, shown as P)-functionalized reduced graphene oxide (RGO) and borocarbonitride (BC₆N, shown as BCN for simplicity) sheets with layers of negatively charged MoS₂ and MoSe₂ have been synthesized by a solution process. The nanocomposites exhibit superior photocatalytic hydrogen evolution reaction (HER) activity compared to the individual components, with the value increasing with the MoS₂/MoSe₂ content. The highest photocatalytic HER activity obtained is 11230 μmol h^–1 g^–1 in the nanocomposite P.RGO-MoS₂, with a P.RGO-MoS₂ ratio of 1:5. The P.RGO-MoSe₂ (1:5) and P.BCN-MoS₂ (1:5) nanocomposites exhibit somewhat lower activities of 9540 and 8593 μmol h^–1 g^–1, respectively. Prompted by literature reports that carbon-rich BCNs are efficient HER electrocatalysts, we have examined the electrocatalytic HER activity of P.BCN-MoS₂ (1:1, 1:5, and 1:7) nanocomposites. The electrocatalytic HER activity of P.BCN-MoS₂ (1:5) is found to be extraordinary, with an onset potential of −50 mV (vs RHE), comparable to that of platinum.