Rational design of ultrahigh porosity Co foam supported flower-like FeNiP-LDH electrocatalysts towards hydrogen evolution reaction

Recent Development of Electrodes Construction for HER in Electrocatalytic Water Splitting

Production of hydrogen (H2) fuel using the hydrogen evolution reaction (HER) through electrocatalysis of water splitting is inexpensive, has optimal performance, and offers remarkable stability. Developing electrocatalysts with excellent stability and high efficiency has been a significant and challenging factor for practical applications of HER for decades. Hydrogen generation occurs on the HER electrode due to the emission of bubbles, proton diffusion, and the transfer of electrons. These considerations should be taken into account during the construction and development of the electrode. This review offers a synopsis of recent advancements in various electrodes used as a base for electrocatalysts, such as nickel foam, titanium foil, copper foam, carbon foam, and others, and discusses their HER catalytic activity, with a focus on the emission of bubbles, diffusion of ions, the structure of the electrode, and the formulation and preparation process. In conclusion, we provide an overview of ideas to further improve and address the significant issues in the manufacture of HER electrodes.

In-situ stabilization of metal-nitride sites in sprouted 2D cMOF@LDHs hetero-nano petals on metaloxynitrides nanostems for enhanced water splitting

Addressing the challenges of enhancing water-splitting efficiency necessitates the exploration and rational design of high-performance and durable electrocatalysts with appealing nanoarchitectures. In this study, we present the design and fabrication of conjugated cMOF/LDH hetero-nano petals decorated with monodispersed Metal-N sites, which are uniformly shelled over tungsten oxynitride (WNO) nanowire arrays to form a unique core-shell architecture. For this rational engineering, WNO nanowire arrays were grown on carbon cloth. Then, a thin-layered Ru-Co-Fe layered double hydroxide (RuCoFe/LDH) was deposited around these wires, resulting in a highly porous three-dimensional array of hierarchical hetero RuCoFe-LDHs@WNO-NWs core-shell nanowires (RuCoFe-NSs@WNO-NWs). Subsequently, the linkers coordinated with the RuCoFe-LDH nanosheets and transformed them in-situ into the RuCoFe-cMOF nano petals (RuCoFe-NPs@WNO-NWs). Notably, the linker's amino groups functioned as hooks for precisely anchoring and stabilizing metal sites, forming the metal nitride (M-N) moieties. Interestingly, the designed bi-functional catalyst exhibited superior catalytic activities for both OER (230 mV @ 10 mAcm-2) and HER (49 mV @ 10 mAcm-2) in an alkaline medium. Additionally, an electrolyzer cell employing Ru-CoFe-NPs@WNO-NWs as a bi-functional electrocatalyst required 1.49V to reach a current density of 10 mA cm-2. These remarkable catalytic performances can be attributed to several key factors, including opulent exposed active sites, an efficient charge/mass transport pathway, an optimized electronic structure, and an interfacial synergy effect. Hence, this study provides a new perspective for the design of efficient bi-functional electrocatalysts for use in the energy related electrochemical devices.

Anchoring cobalt molybdenum nickel alloy nanoparticles on molybdenum dioxide nanosheets as efficient and stable self-supported catalyst for overall water splitting at high current density

Developing bifunctional electrocatalysts with efficient and stable catalytic performance at high current density to improve the productivity of water splitting is important for relieving the environmental pollution and energy crisis. Herein, the Ni₄Mo and Co₃Mo alloy nanoparticles were anchored on MoO₂ nanosheets (H-NMO/CMO/CF-450) by annealing the NiMoO₄/CoMoO₄/CF (CF: self-made cobalt foam) under Ar/H₂ atmosphere. Benefitting from the nanosheets structure, synergistic effect of the alloys, existence of oxygen vacancy and the cobalt foam with smaller pore sizes as conductive substrate, the self-supported H-NMO/CMO/CF-450 catalyst demonstrates outstanding electrocatalytic performance, which delivers small overpotential of 87 (270) mV at 100 (1000) mA·cm^-2 for HER and 281 (336) mV at 100 (500) mA·cm^-2 for OER in 1 M KOH. Meanwhile, the H-NMO/CMO/CF-450 catalyst is used as working electrodes for overall water splitting, which just require 1.46 V @ 10 mA·cm^-2 and 1.71 V @ 100 mA·cm^-2, respectively. More importantly, the H-NMO/CMO/CF-450 catalyst can stabilize for 300 h at 100 mA·cm^-2 in both HER and OER. This research provides an idea for the preparation of stable and efficient catalysts at high current density.