Electrocatalysts of the hydrogen evolution and oxidation reactions (HER and HOR) are of critical importance for the realization of future hydrogen economy. In order to make electrocatalysts economically competitive for large-scale applications, increasing attention has been devoted to developing noble metal-free HER and HOR electrocatalysts especially for alkaline electrolytes due to the promise of emerging hydroxide exchange membrane fuel cells. Herein, we report that interface engineering of Ni3N and Ni results in a unique Ni3N/Ni electrocatalyst which exhibits exceptional HER/HOR activities in aqueous electrolytes. A systematic electrochemical study was carried out to investigate the superior hydrogen electrochemistry catalyzed by Ni3N/Ni, including nearly zero overpotential of catalytic onset, robust long-term durability, unity Faradaic efficiency, and excellent CO tolerance. Density functional theory computations were performed to aid the understanding of the electrochemical results and suggested that the real active sites are located at the interface between Ni3N and Ni.

Robust proton-independent electron reservoirs of (ferrocenylmethyl) trimethylammonium chloride and Na 4 [Fe(CN) 6 ] are utilized to separate H 2 evolution from O 2 evolution with much lower voltage inputs than that of conventional water-splitting electrolysis. Such decoupled water splitting can be readily driven by photovoltaics with small photovoltages in near-neutral solution under natural sunlight irradiation. The electron reservoirs can facilitate sustainable H 2 production from decoupled water splitting and further integrate H 2 evolution with organic upgrading, yielding two value-added products (H 2 and 2,5furandicarboxylic acid).

An efficient strategy to downsize the metal nanoparticles (NPs) and provide basic sites located nearby for optimizing the catalytic performance of the reduced graphene oxide (rGO)-supported metal catalysts has been explored, for the first time, by the potent alkalization of rGO with diamine. By virtue of the coordination effects between the metal ions and the amine groups ligated to rGO, monodispersed Pd nanoparticles (diameter ≤ 1.5 nm) can be facilely anchored on the diamine-alkalized rGO by a simple reduction approach. The turnover frequency (TOF) for heterogeneously catalyzed decomposition of formic acid reaches 3810 h -1 at 323 K, the highest value ever reported under ambient conditions compared to the other heterogeneous catalysts.Supported metal nanoparticles (NPs), as a class of very promising nanocatalysts, have received great interest. Nevertheless, the syntheses of well-dispersed ultrafine metal NPs remain a great challenge. The structure and property of support materials are crucial for controlling the growth of metal NPs and thus improving the catalytic performance. 1 Reduced graphene oxide (rGO) consisting of chemically converted monolayer carbon atoms has emerged as one of the most promising supports for metal NPs because the unique advantage of hydrophilicity and large specific surface area of its precursor, graphene oxide (GO), makes it possible to anchor metal NPs in the solution-based controlled reduction. 2 However, due to its two-dimensional basal plane structure and the negligible interactions between GO and metals, it is still a major obstacle to obtain monodispersed metal particles with very small sizes on GO, where it is difficult to perfectly overcome the aggregation of NPs. 3 Rational modification of the GO surfaces with electron-rich functional groups would facilitate the dispersion of the metal precursors on the support and control the size during the growth of metal NPs. Moreover, such modification may also provide an opportunity to tailor the electronic properties and alkalinity/acidity of GO, and thus optimize the catalytic performance of the resultant catalysts. Nevertheless, a well-defined and controllable surface modification strategy of pristine GO is still lacking.Hydrogen is considered as a promising candidate for satisfying the increasing demand for the sustainable and clean energy supply. Formic acid (FA) has attracted tremendous research interest for hydrogen storage. 4 Recently, selective and efficient decomposition of FA has been achieved with homogeneous organometallic catalysts. 5 Compared to homogeneous catalysts, in general, heterogeneous catalysts are easily separated, controlled and recycled. 6 For practical application, the development of heterogeneous catalysts with high performance for hydrogen generation from FA is urgently desired. Herein, for the first time, we report the immobilization of ultrafine Pd NPs on diamine-alkalized reduced graphene oxide, PDA-rGO (PDA = 1,4-phenylenediamine), which exhibits the highest TOF value (3810 h -1 , 323 K), for FA decom...

Hydrogen (H 2 ) electrochemistry primarily consists of two reactions: hydrogen evolution reaction in water for H 2 production (HER) and hydrogen oxidation reaction in hydrogen fuel cells for H 2 utilization (HOR). The realization of future hydrogen economy necessitates the development of low-cost and competent electrocatalysts for both HER and HOR. Herein, we report that partial nitridation of cobalt nanoparticles on current collectors results in rich Co 2 N/Co interfacial sites, which exhibit bifunctional activity for hydrogen electrochemistry, rivaling the state-of-the-art Pt counterparts tested under similar conditions. Our combined experimental and theoretical computation results demonstrate that Co 2 N/Co interfacial sites not only possess optimal hydrogen adsorption energy but also facilitate water adsorption and dissociation on the catalyst surface, all of which are beneficial to the electrocatalytic performance for both HER and HOR. In addition, our Co 2 N/Co electrocatalysts also demonstrate great tolerance against CO poisoning during long-term H 2 oxidation.