Carbon-incorporated Ni2P-Fe2P hollow nanorods as superior electrocatalysts for the oxygen evolution reaction

Interface-Engineered NiFe/Ni-S Nanoparticles for Reliable Alkaline Oxygen Production at Industrial Current: A Sulfur Source Confinement Strategy

Using powder-based ink appears to be the most suitable candidate for commercializing the membrane electrode assembly (MEA), while research on the powder-based NPM catalyst for anion exchange membrane water electrolyzer (AEMWE) is currently insufficient, especially at high current density. Herein, a sulfur source (NiFe Layered double hydroxide adsorbedSO 4 2 - ${\mathrm{SO}}_4^{2 - }$ ) confinement strategy is developed to integrate Ni3S2 onto the surface of amorphous/crystalline NiFe alloy nanoparticles (denoted NiFe/Ni-S), achieving advanced control over the sulfidation process for the formation of metal sulfides. The constructed interface under the sulfur source confinement strategy generates abundant active sites that increase electron transport at the electrode-electrolyte interface and improve ability over an extended period at a high current density. Consequently, the constructed NiFe/Ni-S delivers an ultra-low overpotential of 239 mV at 10 mA cm-2 and 0.66 mAcm ECSA - 2 ${\mathrm{cm}}_{{\mathrm{ECSA}}}^{ - 2}$ under an overpotential of 300 mV. The AEMWE with NiFe/Ni-S anode exhibits a cell voltage of 1.664 V @ 0.5 A cm-2 and a 400 h stability at 1.0 A cm-2.

Design and multilevel regulation of transition metal phosphides for efficient and industrial water electrolysis

Renewable energy electrolysis of water to produce hydrogen is an effective measure to break the energy dilemma. However, achieving activity and stability at a high current density is still a key problem in water electrolyzers. Transition metal phosphides (TMPs), with high activity and relative inexpensiveness, have become excellent candidates for the production of highly pure green hydrogen for industrial applications. In this mini-review, multilevel regulation strategies including nanoscale control, surface composition and interface structure design of high-performance TMPs for hydrogen evolution are systematically summarized. On this basis, in order to achieve large-scale hydrogen production in industry, the hydrogen evolution performance and stability of TMPs at a high current density are also discussed. Peculiarly, the practical application and requirements in proton exchange membrane (PEM) or anion exchange membrane (AEM) electrolyzers can guide the advanced design of regulatory strategies of TMPs for green hydrogen production from renewable energy. Finally, the challenges and prospects in the future development trend of TMPs for efficient and industrial water electrolysis are given.

Regulating the electronic structure of Ni2P by one-step Co, N dual-doping for boosting electrocatalytic performance toward oxygen evolution reaction and urea oxidation reaction

The development of efficient bifunctional electrocatalysts for oxygen evolution reaction (OER) and urea oxidation reaction (UOR) is critical for hydrogen production and wastewater purification. In this work, we propose a facile synthetic method for Co and N dual-doped Ni2P directly grown on Ni foam (Co-Ni2P-N/NF) using hydrothermal and annealing process. Simultaneous Co and N dual-doping into Ni2P not only modifies the surface electronic structure, but also generates a multitude of active sites with high valence states, which are beneficial for improving electrocatalytic kinetics for both OER and UOR. As a result, the Co-Ni2P-N/NF catalyst exhibits a low overpotential of 329 mV to deliver a current density of 100 mA cm-2 for OER in alkaline solution, which is much lower than that of the state-of-the-art RuO2 electrocatalyst. In addition, the urea-assisted water oxidation process exhibits a significant reduction of approximately 163 mV in the required potential at 100 mA cm-2 compared to that of the OER, which highlights the remarkable potential of the prepared Co-Ni2P-N/NF electrocatalyst in facilitating the purification of wastewater and hydrogen production with significantly lower energy consumption.

Metal-Organic Framework Derived Ni2P/FeP@NPC Heterojunction as Stability Bifunctional Electrocatalysts for Large Current Density Water Splitting

The construction of heterojunction has been widely accepted as a prospective strategy for the exploration of non-precious metal-based catalysts that possess high-performance to achieve electrochemical water splitting. Herein, we design and prepare a metal-organic framework derived N, P-doped-carbon-encapsulated Ni₂P/FeP nanorod with heterojunction (Ni₂P/FeP@NPC) for accelerating the water splitting and working stably at industrially relevant high current densities. Electrochemical results confirmed that Ni₂P/FeP@NPC could both accelerate the hydrogen and oxygen evolution reactions. It could substantially expedite the overall water splitting (1.94 V for 100 mA cm^-2) which is close to the performance of RuO₂ and the Pt/C couple (1.92 V for 100 mA cm^-2). In particular, the durability test exhibited that Ni₂P/FeP@NPC delivers 500 mA cm^-2 without decay after 200 h, demonstrating the great potential for large-scale applications. Furthermore, the density functional theory simulations demonstrated that the heterojunction interface could give rise to the redistribution of electrons, which could not only optimize the adsorption energy of H-containing intermediates to achieve the optimal ΔG_H* in a hydrogen evolution reaction, but also reduce the ΔG value in the rate-determining step of an oxygen evolution reaction, thus improving the HER/OER performance.