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[Display omitted] • Co-MOF is used to uptake SeO 3 2−, and the capacity reaches to 280.0 mg g−1. • R-CoSeO 4 is recycled as an OER electrocatalyst in wastewater treatment process. • Co-Co 0.85 Se, an efficient HER electrocatalyst, is obtained by calcining of R-CoSeO 4. • R-CoSeO 4 /CC and Co-Co 0.85 Se/CC are constructed a cell for water electrolysis. A nanosheet-like cobalt-based metal-organic-framework (Co-MOF) is employed to uptake SeO 3 2− anions, and the remove capacity of Co-MOF reaches a record of 280.0 mg g−1. After uptake SeO 3 2− by Co-MOF, the recycling defect-rich CoSeO 4 (R-CoSeO 4) is used as an electrocatalyst for oxygen evolution reaction (OER), which displays an overpotential of 265 mV at 10 mA cm−2 in 1 M KOH. Furthermore, cobalt-cobalt selenide heterojunction nanoparticle (Co-Co 0.85 Se), a high-performance hydrogen evolution reaction (HER) electrocatalyst (overpotential of 97 mV at 10 mA cm−2 in 1 M KOH) is obtained by one-step calcining of R-CoSeO 4. Series experiments and density functional theory calculations confirm the anion vacancy in R-CoSeO 4 and heterojunction in Co-Co 0.85 Se can improve the OER and HER activity, respectively. Finally, two binder-free electrodes (R-CoSeO 4 /CC and Co-Co 0.85 Se/CC) are employed as anode and cathode, respectively, to construct a water electrolysis cell, which only needs 1.47 V to achieve 10 mA cm−2 in 1 M KOH. [ABSTRACT FROM AUTHOR]

A new catalyst, atomic isolated Ru SAs on N-doped Mo 2 C NSs were fabricated by an anti-Ostwald ripening method (Ru SAs/N-Mo 2 C NSs), exhibited superior HER activity with a mass activity of 7-fold greater than that of 20 wt% Pt/C at an overpotential of 100 mV vs. RHE. • A simple and versatile anti-Ostwald ripening method was employed to fabricate the Ru SAs/N-Mo 2 C NSs. • The mass activity of Ru SAs/N-Mo 2 C NSs was 7-fold greater than 20 wt% Pt/C at an overpotential of 100 mV. • The Ru SAs/N-Mo 2 C NSs possessed the robust HER catalytic stability at high current densities. • The enhanced HER mechanism of the Ru SAs/N-Mo 2 C NSs was revealed by density function theory calculations. The irreversible sintering of supported ruthenium (Ru) catalyst in the preparation process has seriously affected its hydrogen evolution reaction (HER) activity and stability. Herein, ultrathin nitrogen-doped molybdenum carbide nanosheets (N-Mo 2 C NSs) is used as a versatile support to stabilize Ru single atoms (SAs) sites via the anti-Ostwald ripening. Ru SAs are dispersed into the N-Mo 2 C NSs matrix via the strong bonding between the Ru atoms and Mo 2 C NSs regulated by N doping. The atomic isolated Ru SAs are confirmed by spherical aberration correction transmission electron microscopy (AC HAADF-STEM) and X-ray absorption fine structure (XAFS) measurements. Ru SAs/N-Mo 2 C NSs exhibits outstanding HER performance, with a small overpotential of 43 mV at 10 mA/cm2, and robust catalytic stability in 1.0 M KOH. Importantly, Ru SAs/N-Mo 2 C NSs possesses a higher mass activity of 6.44 A/mg Ru than that of 20 wt% Pt/C (0.91 A/mg Pt) at the overpotential of 100 mV. Theoretical calculations further reveal that the high HER activity of Ru SAs/N-Mo 2 C NSs is derived from the synergistically accelerated the dissociation of H 2 O and the optimized H adsorption strength in Mo-Ru interface. This result provides a new direction for the rational designing monatomic electrocatalysts for HER via support interaction effect. [ABSTRACT FROM AUTHOR]

The efficient electrocatalysts for hydrogen evolution reaction (HER) are indispensable. Herein, Mo 2 C micropillars decorated with Pt nanoparticles (<4 nm) on Mo foil (Pt/Mo 2 C-L/Mo) are synthesized by laser ablation in a focused mode in CH 4 atmosphere and laser-induced reduction in an under-focused mode in Ar/H 2 atmosphere. The Pt/Mo 2 C-L/Mo possesses excellent HER performance (21 mV at 10 mA cm−2) and stability (1317 mA cm−2 for 100 h) in acid media. Integrated gas diffusion and catalytic electrodes of Pt/Mo 2 C-L/Mo are constructed by laser in a mixed model and used in proton exchange membrane water electrolyzer (PEMWE). The voltage of the constructed PEMWE of (−) Pt/Mo 2 C-L/Mo || IrO 2 /Ti (+) (1.55 V at 10 mA cm−2) is lower than that of (−) 20 wt.% Pt/C || IrO 2 (+) (1.69 V at 10 mA cm−2) for overall water splitting. This work provides a universal laser synthetic strategy of integrated electrodes with promising application in the field of hydrogen energy. [Display omitted] • The Pt anchored Mo 2 C micropillars (Pt/Mo 2 C-L/Mo) were rapidly fabricated by laser at normal temperature. • The Pt/Mo 2 C-L/Mo possessed high active HER performance and large current density stability in acid media. • The integrated Pt/Mo 2 C-L/Mo electrode simplified the structure of proton exchange membrane water electrolyzer (PEMWE). • The simplified PEMWE of (−) Pt/Mo 2 C-L/Mo||IrO 2 /Ti (+) performed an excellent water splitting performance. [ABSTRACT FROM AUTHOR]