Search

Efficient and robust bifunctional non-precious metal electrocatalysts, used for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), are crucial to develop water splitting commercial applications. Herein, a bottom-up self-assembly strategy is proposed to construct ternary electrocatalysts of nitrogen-doped graphene-like carbon layers encapsulated Mo x C (x = 1, 2) and Ni 3 Fe alloy nanoparticles (Mo x C/Ni 3 Fe@GL) for efficient water electrolysis. The optimized sample (0.27Mo x C/Ni 1.5 Fe@GL, 0.27 represent the mass of ammonium molybdate in the precursor) requires overpotentials (η 10) of 88 and 150, 265 mV in 0.5 M H 2 SO 4 for HER and 1.0 M KOH for HER and OER, respectively. Furthermore, as a bifunctional electrocatalyst in a two-electrode cell, 0.27Mo x C/Ni 1.5 Fe@GL requires only 1.523 V at 10 mA cm−2, which surpasses the noble metal RuO 2 (+)||Pt/C(−) in 1.0 M KOH electrolyte, and shows excellent stability by working at 20 mA cm−2 long as 150 h. The superior electrocatalytic performance can mainly originate from Mo x C and Ni 3 Fe alloys synergistically effected results. The partial doping of Ni or Fe atoms into Mo 2 C optimizes the electronic structure, making the intrinsic activity enhanced. On the other hand, the incorporation of Mo x C heterophases effectively inhibits the Ni 3 Fe nanoparticles agglomeration, benefitting to expose more active sites. Moreover, the protection of encapsulated thin N-doped graphene-like carbon layers for the nanoparticles against corrosion, guarantees the long-time durability. This work provides a potential general bottom-up self-assembly approach to construct high-performance electrocatalysts with multiphase heterostructures with enriched abundant active sites and enhanced intrinsic activity for energy coversion fields. Ternary Mo x C (x = 1, 2) and Ni 3 Fe alloy nanoparticles encapsulated in N-doped graphene-like carbon layers (Mo x C/Ni 3 Fe@GL) are synthesized by a bottom-up self-assembly method. Mo x C/Ni 3 Fe@GL exhibits efficient and stable electrocatalytic water splitting performance. [Display omitted] • Mo x C/Ni 3 Fe@GL was prepared by a facile bottom-up self-assembly strategy. • The synergistic effect of Mo x C and Ni 3 Fe alloy enhanced the intrinsic activity. • N-doped graphene-like thin carbon layers improved the conductivity and stability. • Water splitting required only 1.523 V to reach 10 mA cm−2 and stably for 150 h. [ABSTRACT FROM AUTHOR]

Electrocatalysts with a high oxygen evolution reaction (OER) activity are very important for electrochemical water oxidation, but they are also challenging. In this study, N-doped graphene-like supported highly dispersed bimetallic NiCoP NPs as an efficient electrocatalyst for water oxidation were prepared by using cation exchange resin as a carbon source and by loading cobalt and nickel on D001 by a high-temperature calcination method. The designed electrocatalyst with bimetallic phosphide as the active center shows excellent OER catalytic performance, with an overpotential of 324 mV at 10 mA cm−2 and a corresponding Tafel slope of 97.28 mV dec−1. The increase in NiCoP-3@GL activity may be due to the increase in surface area (933.49 m2 g−1) caused by the irregular morphology, rich interface contact, and porous structure. In addition, the strong combination of NiCoP and GL improves the structural stability and durability of the electrocatalyst. After 5000 cyclic voltammetry tests, the performance of the catalyst decreased by 16.9 %. This work provides a new idea for designing efficient bimetallic phosphide electrocatalysts. [ABSTRACT FROM AUTHOR]

The development of efficient bifunctional catalysts for oxygen reduction and evolution reactions (ORR and OER) is important in the development of rechargeable metal–O2 (air) batteries. Here, a straightforward synthesis of highly efficient bifunctional OER/ORR catalysts MnNiFe/LIG (M111/LIG and M311/LIG where the numbers reflect the relative molar ratio of Mn, Ni, and Fe species) is presented through a facile re‐lasing method. The MnNiFe/LIG shows promising performance in Li–O2 and Li–air batteries without the presence of a redox mediator. The Li–O2 battery with M311/LIG catalysts is reliably discharged and charged for 150 cycles while the discharge potential slightly increases by 0.24 V. The Li‐breathing air battery with M311/LIG catalyst is stable during 350 cycles while the Li‐breathing air battery with M111/LIG catalyst is stable for ≈300 cycles. The function of the M111/LIG and M311/LIG catalysts in the Li–O2 batteries and the influence of the catalysts on the discharge and decomposition products are also investigated. This study promotes further development in carbon–metal oxide composite cathode catalysts for metal–air batteries and underscores the efficacy of laser‐induced graphene for electrode fabrications. [ABSTRACT FROM AUTHOR]

Recently, the pivotal to electrocatalytic water splitting is developing efficient and earth-abundant electrocatalysts to accelerate the sluggish kinetics of hydrogen and oxygen evolution reactions (HER and OER). In this work, (NH 4) 2 MoS 4 derived from polyoxometalates ((NH 4) 6 Mo 7 O 24 ·4H 2 O) were immobilized onto the ion exchange resin D314, and highly dispersed Co-molybdenum disulfide (Co–MoS 2 @NG-4) on nitrogen-doped graphene catalyst was prepared. The optimized Co–MoS 2 @NG-4 shows excellent electrocatalytic performance for HER and OER. Specifically, the low overpotentials of 202 and 352 mV are required to drive the current density of 10 mA cm−2 with the small Tafel slope of 77.30 and 153.50 mV dec−1 for HER and OER, respectively. The Co–MoS 2 @NG-4 demonstrates excellent stability, maintaining a robust operation for 5000 cyclic tests with no detectable stability decay. Porous structure endows Co–MoS 2 @NG-4 with more active centers, increasing its specific surface area and ultimately improving its catalytic performance. [Display omitted] • Synthesized Co–MoS 2 @NG-4 catalyst using ion-exchange and thermal reduction methods. • The porous structure and heteroatom doping improve the electrocatalytic activity. • The Co–MoS 2 @NG-4 exhibits excellent electrochemical activity for both HER and OER. • The Co–MoS 2 @NG-4 exhibits exceptional stability. [ABSTRACT FROM AUTHOR]

The oxygen evolution reaction (OER) is a key half-reaction in renewable energy-related technologies, such as the electrocatalytic water splitting process and carbon dioxide reduction reaction. Unfortunately, developing an efficient and stable electrocatalyst to overcome the sluggish kinetics of OER remains a challenge. Herein, uniformly dispersed NiO and FeNi 3 alloy nanoparticles anchored on N-doped porous carbon (NC) electrocatalysts were designed and synthesized by a facile two-step calcination strategy. The influence of calcination temperature and the molar ratio of Ni:Fe on electrocatalytic OER activity was particularly studied. With an optimal calcination temperature and Ni/Fe ratio, FeNi 3 @NC-800 exhibited outstanding OER performance with a low overpotential of 242 mV at a current density of 10 mA cm−2 and a small Tafel slope of 34.7 mV dec−1 in alkaline media. The enhanced OER activity of FeNi 3 @NC-800 is mainly due to the synergistic effect of FeNi 3 alloy nanoparticles with NC and the high electrical conductivity between FeNi 3 and NC. This research will offer a new perspective on the construction of efficient and stable non-noble metal OER electrocatalyst. • Uniformly dispersed FeNi 3 NPs anchored on NC were designed and synthesized. • The electrocatalysts exhibited outstanding OER performance in alkaline media. • The activity owing to the synergistic effect and uniform dispersion. • The tight connection between FeNi 3 and NC improve the conductivity and stability. [ABSTRACT FROM AUTHOR]