Bifunctional WC-Supported RuO2 Nanoparticles for Robust Water Splitting in Acidic Media.

We report the strong catalyst-support interaction in WC-supported RuO2 nanoparticles (RuO2 -WC NPs) anchored on carbon nanosheets with low loading of Ru (4.11 wt.%), which significantly promotes the oxygen evolution reaction activity with a η10 of 347 mV and a mass activity of 1430 A gRu -1 , eight-fold higher than that of commercial RuO2 (176 A gRu -1 ). Theoretical calculations demonstrate that the strong catalyst-support interaction between RuO2 and the WC support could optimize the surrounding electronic structure of Ru sites to reduce the reaction barrier. Considering the likewise excellent catalytic ability for hydrogen production, an acidic overall water splitting (OWS) electrolyzer with a good stability constructed by bifunctional RuO2 -WC NPs only requires a cell voltage of 1.66 V to afford 10 mA cm-2 . The unique 0D/2D nanoarchitectures rationally combining a WC support with precious metal oxides provides a promising strategy to tradeoff the high catalytic activity and low cost for acidic OWS applications.

Construction of FeP Hollow Nanoparticles Densely Encapsulated in Carbon Nanosheet Frameworks for Efficient and Durable Electrocatalytic Hydrogen Production.

Developing noble-metal-free based electrocatalysts with high activity, good stability, and low cost is critical for large-scale hydrogen production via water splitting. In this work, hollow FeP nanoparticles densely encapsulated in carbon nanosheet frameworks (donated as hollow FeP/C nanosheets), in situ converted from Fe-glycolate precursor nanosheets through carbonization and subsequent phosphorization, are designed and synthesized as an advanced electrocatalyst for the hydrogen evolution reaction. FeP hollow nanoparticles are transformed from intermediate Fe3O4 nanoparticles through the nanoscale Kirkendall effect. The two-dimensional architecture, densely embedding FeP hollow nanoparticles, provides abundant accessible active sites and short electron and ion pathways. The in situ generated carbon nanosheet frameworks can not only offer a conductive network but also protect the active FeP from oxidation. As a result, hollow FeP/C nanosheets exhibit excellent electrocatalytic performance for the hydrogen evolution reaction in 0.5 m H2SO4 with a quite low overpotential of 51.1 mV at 10 mA cm-2, small Tafel slope of 41.7 mV dec-1, and remarkable long-term stability. The study highlights the in situ synthesis of two-dimensional metal phosphide/C nanocomposites with highly porous features for advanced energy storage and conversion.