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[Display omitted] It is a great challenge to design electrode materials with good stability and high specific capacitance for supercapacitors. Herein, a three-dimensional (3D) hydrangea-like NiMoO 4 micro-architecture with Ag nanoparticles anchored on the surface has been designed by adding EDTA-2Na, which was assembled with reduced graphene oxide (rGO) and named as NiMoO 4 -Ag/rGO composite. Benefiting from the synergetic contributions of structural and componential properties, NiMoO 4 -Ag/rGO composite exhibits a high specific capacitance of 566.4 C g−1 at 1 A g−1, and great cycling performance with 90.5% capacitance retention after 1000 cycles at 10 A g−1. The NiMoO 4 -Ag/rGO electrode shows an enhanced cycling stability due to the two-dimensional towards two-dimensional (2D-2D) interface coupling between rGO and NiMoO 4 nanosheets, and the stable 3D hydrangea-like micro-architecture. Moreover, NiMoO 4 -Ag/rGO with 5–15 nm pore structure and enhanced conductivity exhibits improved charge transfer and ions diffusion. Besides, NiMoO 4 -Ag/rGO//AC capacitor displays an outstanding energy density of 40.98 Wh kg−1 at 800 kW kg−1, and an excellent cycling performance with 73.3% capacitance retention at 10 A g−1 after 8000 cycles. The synthesis of NiMoO 4 -Ag/rGO composite can provide an effective strategy to solve the poor electrochemical stability and slow electron/ion transfer of NiMoO 4 material as supercapacitors electrode. [ABSTRACT FROM AUTHOR]

Ru doping and sulfur vacancy engineering synergistically modify the electronic structure of FeNi 2 S 4 to boost electrocatalytic oxygen evolution reaction. [Display omitted] • A facile ion doping and vacancy engineering strategy has been proposed for modifying the electronic structure. • Ru doping and S vacancy concurrently facilitate the surface reconstruction of FeNi 2 S 4. • The in situ formed Ni3+-rich oxyhydroxides are highly active toward OER. • The Ru-FeNi 2 S 4-x catalyst can exhibit outstanding electrocatalytic OER performance. Electronic structure engineering lies at the heart of the catalyst design, however, utilizing one strategy to modify the electronic structure is still challenging to achieve optimal electronic states. Herein, an advanced approach that incorporating both Ru dopants and sulfur vacancies into thiospinel-type FeNi 2 S 4 to synergistically modulate the electronic configuration, is proposed. Deep characterizations and theoretical study reveal that the in-situ formed Ni3+ species are real active centers. Ru doping and sulfur vacancies synergistically tune the electronic states of Ni2+ sites to a near-optimal value, leading to the formation of abundant oxygen evolution reaction (OER)-active Ni3+ species via electrochemical reconstruction. Consequently, the optimized Ru-FeNi 2 S 4 catalyst can exhibit superb electrocatalytic performance towards OER, delivering the overpotentials of 253 mV and 340.8 mV at 10 mA·cm−2 in alkaline water and seawater, respectively. The proper combination of vacancy and heteroatom doping in this work may unlock the catalytic power of conventional catalysts toward electrochemical reactions. [ABSTRACT FROM AUTHOR]

Graphical abstract HNO 3 modified graphite/PTFE cathode with exterior hydrophobic film has more appreciable performance for H 2 O 2 generation than the counterparts. Abstract Electrochemical 2-electrons oxygen reduction process has been regarded as the effective strategy for H 2 O 2 generation in wastewater treatment. However, its large-scale application is still limited by the relatively high cost of the carbon materials and short-term stability. In this study, a nitric acid modified graphite/polytetrafluoroethylene (PTFE) composite cathode with exterior hydrophobic film was fabricated for cost-effective electrogeneration of hydrogen peroxide (H 2 O 2). Experimental results show that 2 M HNO 3 modification rendered the introduction of much more defect sites and oxygen/nitrogen-containing groups on graphite. As a result, H 2 O 2 electrogeneration was 3.0 times as much as that of virgin graphite counterpart at 3 mA cm−2. Moreover, the additional introduction of exterior hydrophobic film on the as-prepared graphite/PTFE cathode did not only further promote H 2 O 2 electrogeneration, but also endowed the cathode with strong hydrophobic stability. As for the modified cathode with exterior hydrophobic film, the influence of mass graphite/PTFE binder ratio (1:1–4:1) and pH (3.0–9.0) on H 2 O 2 electrogeneration was slight, but the current density (3.0–15 mA cm−2) had evident effect on H 2 O 2 electrogeneration. Generally, owing to its low price and being easily available, the modified graphite would be cost-effectively utilized to prepare the gas diffusion cathode for the large-scale electrogeneration of H 2 O 2 in industry. [ABSTRACT FROM AUTHOR]