Carbon-coated cobalt molybdenum oxide as a high-performance electrocatalyst for hydrogen evolution reaction.

Synthesis of high-performance and cost-effective catalysts towards the hydrogen evolution reaction (HER) is critical in developing electrochemical water-splitting as a viable energy conversion technique. For non-precious metal Co- and Ni-based catalysts, hydroxides were found to form on the surface of the catalysts under alkaline environments and benefit the catalytic performance, whereas there is limited systematic study on the explicit influence of hydroxides on the electrocatalytic mechanism and performance of these catalysts. Herein, we report a close correlation observed between the amount of the surface hydroxides formed and the resulting electrocatalytic performance of a Co-Mo-O nanocatalyst through careful comprehensive structural and property characterizations. We found that an appropriate amount of hydroxide can be moderated by simply coating the catalyst surface with carbon shells to optimize the catalytic properties. As a result, a carbon-coated Co-Mo-O nanocatalyst was successfully developed and is among the best reported non-precious HER catalysts with a superior electrocatalytic activity and outstanding durability for the HER under alkaline environment. First-principles calculations were further conducted to probe the nature of the active sites and the role of hydroxides in the Co-Mo-O@C/NF catalyst towards the HER.

Highly Dispersed Platinum on Honeycomb-like NiO@Ni Film as a Synergistic Electrocatalyst for the Hydrogen Evolution Reaction.

Platinum (Pt) is well-known as the best-performing catalyst for the hydrogen evolution reaction (HER), but its practical application is severely hindered by its prohibitively high cost and problematic performance in alkaline electrolyte. Herein, we report that the issues of intrinsic activity and cost concern of Pt can be simultaneously addressed by employing a combination of concerted catalysis and nanoengineering strategies. Motivated by our density functional theory (DFT) calculations that the cooperative catalysis between Pt and NiO would lead to a better HER activity in comparison to Pt solely in alkaline solution, we successfully synthesized a Pt/NiO@Ni/NF nanocomposite catalyst by depositing highly dispersed Pt nanoclusters/nanoparticles on a honeycomb-like NiO@Ni film supported on Ni foam (NF). The resulting Pt/NiO@Ni/NF catalyst outperforms the commercial Pt/C catalyst with a high and stable HER activity in alkaline solution and, more impressively, with an economical Pt content as low as ∼0.1 mg cm-2.