Strain-promoted conductive metal-benzenhexathiolate frameworks for overall water splitting

Breaking efficiency Limits in solar water Splitting: Ferroelectric CuInP2Se6 with Ni Single-Atom cocatalysts for enhanced carrier separation and activity

Photocatalytic water splitting represents a promising approach for sustainable energy production, yet its practical implementation remains hindered by insufficient light absorption, rapid charge recombination, and inadequate catalytic efficiency. This study proposes a two-dimensional ferroelectric Ni2/CuInP2Se6 that addresses these fundamental limitations through rational material design. Through systematic screening of ABP2X6 materials (A=Cu; B = In/Cr; X=S/Se), the ferroelectric CuInP2Se6 monolayer emerges as an optimal substrate due to its exceptional stability, appropriate band alignment, and superior light absorption coefficient. Subsequent selection of Ni single-atom cocatalysts from nine transition metals reveals optimal hydrogen evolution (ηHER = 0.09 V) and oxygen evolution (ηOER = 0.37 V) overpotentials, achieving remarkable solar-to-hydrogen efficiency (24.63 %). Crucially, the ferroelectric polarization-induced built-in electric field enables spatial separation of photogenerated carriers while modulating the Ni d-band center, which effectively regulates the adsorption strength of reaction intermediates, facilitating the adaptive optimization of distinct reaction. The proposed strategy not only demonstrates the viability of 2D ferroelectric materials for photocatalytic applications but also establishes a general framework for designing high-performance photocatalysts through coupled polarization engineering and single-atom catalysis.

In-situ synthesis to promote surface reconstruction of metal-organic frameworks for high-performance water/seawater oxidation

Metal-organic frameworks (MOFs) have gained tremendous notice for the application in alkaline water/seawater oxidation due to their tunable structures and abundant accessible metal sites. However, exploring cost-effective oxygen evolution reaction (OER) electrocatalysts with high catalytic activity and excellent stability remains a great challenge. In this work, a promising strategy is proposed to regulate the crystalline structures and electronic properties of NiFe-metal-organic frameworks (NiFe-MOFs) by altering the organic ligands. As a representative sample, NiFe-BDC (BDC: C8H6O4) synthesized on nickel foam (NF) shows extraordinary OER activity in alkaline condition, delivering ultralow overpotentials of 204, 234 and 273 mV at 10, 100, and 300 mA cm-2, respectively, with a small Tafel slope of 21.6 mV dec-1. Only a slight decrease is observed when operating in alkaline seawater. The potential attenuation is barely identified at 200 mA cm-2 over 200 h continuous test, indicating the remarkable stability and corrosion resistance. In-situ measurements indicate that initial Ni2+/Fe2+ goes through oxidation process into Ni3+/Fe3+ during OER, and eventually presents in the form of NiFeOOH/NiFe-BDC heterojunction. The unique self-reconstructed surface is responsible for the low reaction barrier and fast reaction kinetics. This work provides an effective strategy to develop efficient MOF-based electrocatalysts and an insightful view on the dynamic structural evolution during OER.

Synthesis of self-supported NiCoFe(OH)x via fenton-like effect corrosion for highly efficient water oxidation

Efficientandinexpensiveoxygenevolutionreaction(OER)catalysts are essential for the electrochemical splitting of water into hydrogen fuel. Herein, we have successfully synthesized NiCoFe(OH)x nanosheets on Ni-Fe foam (NFF) by exploiting the Fenton-like effect of Co2+ and S2O82- to corrode the NFF foam. The as-prepared NiCoFe(OH)x/NFF exhibits the porous structure with the interconnected nanosheets that are firmly bonded to the conductive substrate of NFF, thereby enhancing ions and charge transfer kinetics. The unique structure and composition of NiCoFe(OH)x/NFF result in the low overpotentials of 200 and 262 mV at current densities of 10 and 100 mA cm-2, respectively, as well as a low Tafel slope of 53.25 mV dec-1. In addition, NiCoFe(OH)x/NFF displays low overpotentials of 267 and 294 mV at a high current density of 100 mA cm-2 in simulated and real seawater, respectively. Furthermore, the assembled NiCoFe(OH)x//Pt/C water electrolysis cell has achieved a current density of 10 mA cm-2 at a low voltage of 1.49 V, and displayed the good stability with slight attenuation for 110 h. The high OER performance of NiCoFe(OH)x is attributed to the co-catalytic effect of the three metal ions and the interconnected porous nanosheet structure.

Ultrasound-Assisted Preparation and Performance Regulation of Electrocatalytic Materials

With the advancement of scientific research, the introduction of external physical methods not only adds extra freedom to the design of electro-catalytical processes for green technologies but also effectively improves the reactivity of materials. Physical methods can adjust the intrinsic activity of materials and modulate the local environment at the solid-liquid interface. In particular, this approach holds great promise in the field of electrocatalysis. Among them, the ultrasonic waves have shown reasonable control over the preparation of materials and the electrocatalytic process. However, the research on coupling ultrasonic waves and electrocatalysis is still early. The understanding of their mechanisms needs to be more comprehensive and deep enough. Firstly, this article extensively discusses the adhibition of the ultrasonic-assisted preparation of metal-based catalysts and their catalytic performance as electrocatalysts. The obtained metal-based catalysts exhibit improved electrocatalytic performances due to their high surface area and more exposed active sites. Additionally, this article also points out some urgent unresolved issues in the synthesis of materials using ultrasonic waves and the regulation of electrocatalytic performance. Lastly, the challenges and opportunities in this field are discussed, providing new insights for improving the catalytic performance of transition metal-based electrocatalysts.

Structure evolution and durability of Metal-Nitrogen-Carbon (M = Co, Ru, Rh, Pd, Ir) based oxygen evolution reaction electrocatalyst: A theoretical study

Developing low-cost, high activity and stability oxygen evolution reaction (OER) catalysts is significantly important but still challenging for water electrolyzers. In this work, we calculated the OER activity and stability of Metal-Nitrogen-Carbon (MNC, M = Co, Ru, Rh, Pd, Ir) based electrocatalyst with different structures (MN₄C₈, MN₄C₁₀, MN₄C₁₂) using density functional theory (DFT) method. These electrocatalysts were divided into three groups based on the value of ΔG_*OH, that is ΔG_*OH > 1.53 eV (PdN₄C₈, PdN₄C₁₀, PdN₄C₁₂), ΔG_*OH < 1.23 eV (RuN₄C₈, RuN₄C₁₀, RuN₄C₁₂, CoN₄C₈, CoN₄C₁₀) and 1.23 eV < ΔG_*OH < 1.53 eV (RhN₄C₈, RhN₄C₁₀, RhN₄C₁₂, IrN₄C₈, IrN₄C₁₀, IrN₄C₁₂, CoN₄C₁₂), and ΔG_*OH determine whether the structure evolution will appear. The results proved that MNC (M = Rh, Ir) with 1.23 eV < ΔG_*OH < 1.53 eV shows higher OER activity due to moderate binding energy between reaction intermediates and MNC. Furthermore, these catalysts could maintain MNC structure without further oxidation and structural evolution under working conditions (high temperature, dynamic condition, local electric field and strong specific adsorption), therefore show excellent stability. However, MNC electrocatalyst with ΔG_*OH > 1.53 eV or ΔG_*OH < 1.23 eV revealed less stability under working conditions, due to their low intrinsic stability or structural evolution under working conditions, respectively. In conclusion, we proposed a comprehensive evaluation method for MNC electrocatalysts by taking ΔG_*OH as the screening criterion for OER activity and stability, as well as ΔE_b under working condition as descriptor of stability. This is of great significance for the design and screening of ORR, OER and HER electrocatalysts under working conditions.