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Water splitting is an efficient strategy to produce purity hydrogen and convert intermittent electricity from renewable wind and solar sources. In this work, dense NiMoO4 micro-pillars arrays (MPAs) were in-situ grown on nickel foam (NF) through facile hydrothermal method, then the NiMoO4/NF were converted into NiMoO4–P/NF and NiFe/NiMoO4/NF via phosphating and electrodeposition method, respectively. The NiMoO4–P/NF electrode required small overpotentials of 34 mV@10 mA cm−2 and 130 mV@100 mA cm−2 for hydrogen evolution reaction (HER). The NiFe/NiMoO4/NF electrode exhibited excellent oxygen evolution reaction (OER) activity with overpotentials of 210 mV@10 mA cm−2 and 300 mV@100 mA cm−2. The overall water splitting using the anode-cathode couple of NiFe/NiMoO4/NF||NiMoO4–P/NF only consumes low voltages of 1.47 V@10 mA cm−2 for 100 h and 1.66 V@100 mA cm−2 for 50 h in 1 M KOH. The electronic modification and the well-designed hierarchical structure contribute the high energy-efficient and stabile overall water splitting.

A 3D self-supported hierarchical architecture composed of Ni nanoparticle@nitrogen-doped carbon nanotube modified NiMoN micro-pillar arrays grown on Ni foam (Ni@NCNT/NiMoN/NF) was synthesized. Benefiting from the protection by N-doped carbon layers, and the well-designed hierarchical structure with a large surface area, high electrical conductivity and convenient mass/electron transfer paths, this composite shows excellent activity and durability under both acidic and alkaline conditions. It demands extremely low overpotentials of 15 mV and 156 mV in 1.0 M KOH, and 31 and 96 mV in 0.5 M H2SO4 to achieve current densities of 10 and 200 mA cm−2, respectively, which are superior to those for commercial Pt/C and other control samples. DFT calculations prove that the synergetic effect between N-doped carbon, Ni, and NiMoN enhances H2O adsorption and decreases hydrogen adsorption free energy (|ΔGH*|) to facilitate the HER process. Furthermore, the composite possesses extraordinary antioxidation ability under the conditions of the cyclic current pulse and power-off–on state. This work suggests an effective pathway to enhance the catalytic activity and oxidation resistance by building a hierarchical structure encapsulated by thin N-doped carbon layers, showing promising potency as the HER electrode in practical energy conversion and storage systems of wind power and solar power.

In consideration of urgent need to detect trace nitroaromatic contaminants (NACs) in the environment, an ultrasensitive environmental sensing for NACs detection based on Prussian blue analogues cubes in situ grown on glucose-derived porous carbon materials (PBAcs/PC-x) was synthesized for the first time via a simple one-pot pyrolysis process followed by acid pickling. The prepared PBAcs/PC-800 sensor possesses abundant cyano groups (–CN) with lone-pair electrons, π-conjugated effect of porous carbon and NACs, high conductive carbon lattices and numerous active redox sites on PBAs, which boost the pre-adsorption of NACs, the electron transfer rate and the electrocatalysis activity toward reduction of NACs. Those synergetic effects endow the prepared PBAcs/PC-800/GC electrode with not only wide detection range from 1 to 1000 ppb for dinitrobenzene (DNB) detection but also an clear response to DNB at a level of 1–10 ppb with an extremely high sensitivity of 443.1 μA ppm−1 (6271.8 μA ppm−1 cm−2), a good linearity of 0.9997 and a low detection limit of 0.12 ppb (S/N = 3). Additionally, the proposed sensor possesses high reproducibility, good long-term stability, strong anti-interference ability, and also shows great potential for sensitive detection of NACs at ppb level in environmental water. The present work offers a great model for constructing efficient and promising electrochemical NACs sensor.

Hydrogen-motivated electrolysis of Na2CO3 for energy-saving production of NaOH and CO2/NaHCO3 is realized by the hydrogen oxidation reaction to insert proton into anolyte and the hydrogen evolution reaction to extract proton out of catholyte. Electrolytic voltage at 100 mA cm−2 is as low as 0.88 V; this voltage is only 35% of the voltage used in the traditional electrolysis.