Facet modulation of nickel-ruthenium nanocrystals for efficient electrocatalytic hydrogen evolution.

Constructing highly active electrocatalysts towards hydrogen evolution reaction (HER) in both alkaline and acidic media is essential for achieving a sustainable energy economy. Here, a facile ethylene glycol reduction strategy was employed to design the nickel-ruthenium nanocrystals (Ni-Ru NC) with an exposed highly active Ru (101) facet as an efficient electrocatalyst for HER. Testings show Ni-Ru NC outperforms the benchmark catalyst Pt/C by delivering extraordinarily low overpotentials of 21.1 and 70.9 mV to drive 10 mA cm-2 in acidic and alkaline solutions, respectively. The results of experimental and theoretical studies suggest that Ni can modulate the electronic structure of the Ru NC and optimize the hydrogen adsorption free energy on Ru's surface, which accelerates the charge transfer kinetics and enhances the HER performance. The study support the potential application of facet-modulated Ru-based HER eleccatalyst in an alkaline environment.

In Situ Construction of Bifunctional N-Doped Carbon-Anchored Co Nanoparticles for OER and ORR.

Designing highly active and more durable oxygen electrocatalysts for regenerative metal-air batteries and water splitting is of practical significance. Herein, an advanced Co/N-C-800 catalyst composed of abundant Co-Nx structures and carbon defects derived from cobalt phthalocyanine is synthesized. Remarkably, this catalyst exhibits favorable catalytic performance toward the oxygen evolution reaction (OER) with a receivable overpotential of 274 mV in an alkaline medium achieving a current density of 10 mA cm-2 and a Tafel slope of 43.6 mV decade-1, outperforming the commercial RuO2 catalyst. It further displays a high half-wave potential (0.82 V) for the oxygen reduction reaction in 0.1 M KOH. Theoretical calculations reveal that the Co-Nx active sites along with the carbon defects can decrease the adsorption energy of intermediates (OH*, O*, and OOH*) and enhance the electron-transfer ability, thus boosting the OER process.

Hydrogen-Etched Bifunctional Sulfur-Defect-Rich ReS2 /CC Electrocatalyst for Highly Efficient HER and OER.

The design on synthesizing a sturdy, low-cost, clean, and sustainable electrocatalyst, as well as achieving high performance with low overpotential and good durability toward water splitting, is fairly vital in environmental and energy-related subject. Herein, for the first time the growth of sulfur (S) defect engineered self-supporting array electrode composed of metallic Re and ReS2 nanosheets on carbon cloth (referred as Re/ReS2 /CC) via a facile hydrothermal method and the following thermal treatment with H2 /N2 flow is reported. It is expected that, for example, the as-prepared Re/ReS2 -7H/CC for the electrocatalytic hydrogen evolution reaction (HER) under acidic medium affords a quite low overpotential of 42 mV to achieve a current density of 10 mA cm-2 and a very small Tafel slope of 36 mV decade-1 , which are comparable to some of the promising HER catalysts. Furthermore, in the two-electrode system, a small cell voltage of 1.30 V is recorded under alkaline condition. Characterizations and density functional theory results expound that the introduced S defects in Re/ReS2 -7H/CC can offer abundant active sites to advantageously capture electron, enhance the electron transport capacity, and weaken the adsorption free energy of H* at the active sites, being responsible for its superior electrocatalytic performance.