CoMn phosphide encapsulated in nitrogen-doped graphene for electrocatalytic hydrogen evolution over a broad pH range

Multicore-shell MnO2@Ppy@N-doped porous carbon nanofiber ternary composites as electrode materials for high-performance supercapacitors

In this study, a multicore-shell ternary composite electrode material (MnO₂@Ppy@NPCNFs) with excellent electrochemical performances was prepared by using surface modification, in which core-shell Ppy@N-doped porous carbon nanofibers (Ppy@NPCNFs) with large specific surface area and high conductivity were used as the substrate (a multicore layer), and MnO₂ was loaded on the substrate by hydrothermal synthesis to form a shell layer, further improving the SC of electrode material. The parameters of hydrothermal growth of MnO₂ on Ppy@NPCNFs were explored by means of the control variable method and response surface methodology, and the optimal parameters were predicted and verified. Electrochemical test results showed that the SC of MnO₂@Ppy@NPCNFs prepared under the optimal reaction parameters was as high as 595.77 F g^-1, and its capacitance retention was 96.2 % after 1000 cycles. Moreover, a symmetric supercapacitor prepared with the optimal multicore-shell electrode showed an energy density of 9.36 Wh kg^-1 at a power density of 1000 W kg^-1 and a retention rate of 92.46 % after 1000 cycles, indicating the promising application of multicore-shell ternary composite electrode material in high-performance supercapacitors.

The High Electrocatalytic Performance of NiFeSe/CFP for Hydrogen Evolution Reaction Derived from a Prussian Blue Analogue

Non-noble-metal-based chalcogenides are promising candidates for hydrogen evolution reaction (HER) by harnessing the architectural design and the synergistic effect between the elements. Herein, a porous bimetallic selenide (NiFeSe) nanocube deposited on carbon fiber paper (NiFeSe/CFP) was synthesized through a facile selenization reaction based on Prussian blue analogues (PBAs) as precursors. The NiFeSe/CFP exhibited excellent HER activity with an overpotential of just 186 mV for a current density of 10 mA cm−2 in 1.0 M KOH at ambient temperature, similar to most of the state-of-the-art transition metal chalcogenides. The corresponding Tafel slope was calculated to be 52 mV dec−1, indicating fast discharge of the proton during the HER. Furthermore, the catalyst could endure long-term catalytic tests and showed remarkable durability. The enhanced electrocatalytic performance of NiFeSe/CFP is attributed to the unique 3D porous configuration inherited from the PBA templates, enhanced charge transfer occurring at the heterogeneous interface due to the synergistic effect between the bimetallic phases, and the high conductivity improved by the formation of amorphous carbon shells during the selenization. These findings prove that the combination of inexpensive metal–organic framework precursors and hybrid metallic compounds is a feasible way to realize the performance enhancement of non-noble-metal-based chalcogenides towards alkaline HER.

Three-dimensional reduced graphene oxide decorated with cobalt metaphosphate as high cost-efficiency electrocatalysts for the hydrogen evolution reaction

The development of cost-effective non-noble metal electrocatalysts is critical for the research of renewable energy. Transition metal cobalt metaphosphate-based materials have the potential to replace the noble metal Pt. Hence, in this work, we synthesize three-dimensional graphene-supported cobalt metaphosphate (Co(PO₃)₂-3D RGO) for the first time through the one-step hydrothermal synthesis method at low temperature with the aid of PH₃ phosphating. In a 0.5 mol L⁻¹ H₂SO₄ solution, the obtained electrocatalyst exhibits excellent electrochemical activity for the hydrogen evolution reaction (HER) with a small overpotential of 176 mV at a current density of 10 mA cm⁻² and a Tafel slope of 63 mV dec⁻¹. Additionally, in a 1 mol L⁻¹ KOH solution, the electrocatalyst also shows outstanding HER activity with a small overpotential of 158 mV at a current density of 10 mA cm⁻² and a Tafel slope of 88 mV dec⁻¹. Co(PO₃)₂-3D RGO can maintain its catalytic activity for at least ten hours whether in acid or alkali. This work not only demonstrates an excellent electrocatalyst for the hydrogen evolution reaction, but also provides an extremely convenient preparation technology, which provides a new strategy for the development and utilization of high-performance electrocatalysts.

The development of cost-effective non-noble metal electrocatalysts is critical for the research of renewable energy.

3D nanoporous NiCoP as a highly efficient electrocatalyst for the hydrogen evolution reaction in alkaline electrolyte

3D nanoporous NiCoP properly inherits the dealloyed double-continuous nanoporous structure, enables fast charge transfer, and fully reflects its inherent activity.

Atomic-layered Pt clusters on S-vacancy rich MoS2-x with high electrocatalytic hydrogen evolution

Developing suitable supports to maximize the atomic utilization efficiency of platinum group metals is of great significance to hydrogen evolution from water splitting. Herein, we report a fully exposed Pt cluster supported on an S-vacancy rich MoS2-x support (Pt/Sv-MoS2-x) by a facile impregnation method. Pt/Sv-MoS2-x exhibits an outstanding electrochemical HER performance with a low overpotential of 26.6 mV at a current density of 10 mA cm-2, a small Tafel slope of 34.8 mV dec-1 and good durability. Most importantly, the mass activity of Pt is an order of magnitude more active than that of commercial Pt/C at an overpotential of 0.08 V. We attribute this exceptional HER catalytic performance to the fact that platinum and Sv-MoS2-x act in synergy to accelerate the reaction kinetics.