Constructing built-in electric field via ruthenium/cerium dioxide Mott-Schottky heterojunction for highly efficient electrocatalytic hydrogen production

Ru doped NiMoO4 nanoarray as a high-efficiency electrocatalyst for nitrite reduction to ammonia

The electrocatalytic reduction of nitrite to recyclable ammonia (NH3) is essential to maintain nitrogen balance and meet growing energy requirements. Herein, we report that Ru doped honeycomb NiMoO4 nanosheet with copious oxygen vacancies grown on nickel foam substrate has been prepared by a facile hydrothermal synthesis and immersion process, which can act as an efficient electrocatalyst for NH3 synthesis by reduction of nitrite. By optimizing the concentration of RuCl3 solution, 0.01Ru-NiMoO4/NF possesses excellent NO2-RR performance with NH3 yield of 20249.17 ± 637.42 μg h-1 cm-2 at -0.7 V and FE of 95.56 ± 0.72 % at -0.6 V. When assembled into a Zn-NO2- battery, it provides a remarkable level of power density of 13.89 mW cm-2, outperforming the performance of virtually all previous reports. The efficient adsorption and activation of NO2- over Ru-doped NiMoO4 with oxygen vacancy have been verified by density functional theory calculations, as well as the possible reaction pathway.

Titanium Dioxide and N-Doped Carbon Hybrid Nanofiber Modulated Ru Nanoclusters for High-Efficient Hydrogen Evolution Reaction Electrocatalyst

The designing and fabricating highly active hydrogen evolution reaction (HER) electrocatalysts that can superior to Pt/C is extremely desirable but challenging. Herein, the fabrication of Ru/TiO2/N-doped carbon (Ru/TiO2/NC) nanofiber is reported as a novel and highly active HER electrocatalyst through electrospinning and subsequent pyrolysis treatment, in which Ru nanoclusters are dispersed into TiO2/NC hybrid nanofiber. As a novel support, experimental and theoretical calculation results reveal that TiO2/NC can more effectively accelerate water dissociation as well as optimize the adsorption strength of *H than TiO2 and NC, thus leading to a significantly enhanced HER activity, which merely requires an overpotential of 18 mV to reach 10 mA cm-2, outperforming Pt/C in an alkaline solution. The electrolytic cell composed of Ru/TiO2/NC nanofiber and NiFe LDH/NF can generate 500 and 1000 mA cm-2 at voltages of 1.631 and 1.753 V, respectively. Furthermore, the electrolytic cell also exhibits remarkable durability for at least 100 h at 200 mA cm-2 with negligible degradation in activity. The present work affords a deep insight into the influence of support on the activity of electrocatalyst and the strategy proposed in this research can also be extended to fabricate various other types of electrocatalysts for diverse electrocatalytic applications.