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[Display omitted] • A novel nanomaterial toward (CuCo/CP) electrochemical water splitting. • Facile method for Copper-Cobalt (CuCo) supported on carbon paper (CuCo/CP) composition. • The electrochemical activation of electrode led to improvement of OER and HER kinetics. • Tafel slopes has been calculated for CoCu/CP is 97.7 mV dec−1. • CuCo/CP an emerging material for different energy applications. Electrochemical water splitting is one of the most appealing approaches to produce Hydrogen as a sustainable energy resource. The efficiency of Hydrogen evolution reaction (HER) and Oxygen evolution reaction (OER) largely depends on the activity and stability of any elctrocatalyst. Herein, we have employed a facile and reproducible electrodeposition coating method to synthesize bi-metallic Copper-Cobalt (CuCo) containing electrocatalyst supported on carbon paper (CuCo/CP) for electrochemical splitting of water in neutral medium. We have accomplished superior and improved HER and OER electrocatalytic activity, regardless of lower activity of Cu toward HER and OER. The unique structure and synergistic effect of CuCo/CP displayed better electrocatalytic activity with a low overpotential of 450 mV at 10 mA.cm−2 toward HER and just 80 mV at 10 mA.cm−2 toward Oxygen evolution reaction than other Cu containing electrocatalysts. Moreover, the durability of synthesized electrocatalyst at high applied current density ensure the stable nature of the catalyst. The present study may pave the way for the rational design of electrocatalysts for efficient Oxygen and Hydrogen production applications. [ABSTRACT FROM AUTHOR]

As one of the most efficient, low-cost, and readily available electrocatalysts for oxygen evolution reaction (OER) in alkaline environments, the nickel-iron electrocatalyst is of great significance to commercial water splitting. In this study, NiFe-layered double hydroxide loaded on nickel foam (NiFe-LDH/NF) was synthesized via a simple one-step hydrothermal method, whose OER catalytic performance could be successfully optimized by further electrochemical reconstruction. The results show that NF is an effective precursor to loading crystallized Ni(OH) 2 nanoparticles during hydrothermal synthesis, leading to the generation of high-performance NiOOH during OER reconstruction. Under the optimal Ni:Fe feeding ratio, Ni 2 Fe 1 -LDH/NF requires an ultra-low OER overpotential of 239 mV at 50 mA cm−2 and 260 mV at 100 mA cm−2, whose Tafel slope is only 64.1 mV dec−1. Impressively, Ni 2 Fe 1 -LDH/NF also achieves an ultra-low voltage of 1.44 V at 10 mA cm−2 with excellent long-term stability for overall water splitting. Unlike the previous viewpoint that only Ni species dominate surface reconstruction of NiFe-LDH, in this article the decisive influence related to Fe species on the reconstruction layers' activity and stability is confirmed by electrochemistry, Raman, and XPS analysis during reconstruction process. During OER reconstruction, the surface Ni:Fe ratios can be "self-adaptively" regulated to an appropriate region, thus the stable reconstruction layers rich in NiOOH can be formed as the protective shells for NiFe-LDH. Furthermore, such "self-adaptive" reconstruction, assisted with appropriate initial Ni:Fe feeding ratios, can also stimulate more Ni3+ active sites for OER, benefitting the outstanding catalytic performance of NiFe-LDH/NF for overall water splitting and prospective large-scale application. [Display omitted] • There are some highlights in this paper may be found interested by the general readers. • Unstable iron-rich phases start self-adaptively electrochemical reconstruction. • Self-adaptive reconstruction promotes the OER catalytic activity and stability. • The optimal electrocatalyst exhibits 260 mV overpotential at 100 mA·cm−2 for OER. • The electrocatalyst only needs 1.44 V at 10 mA·cm−2 for overall water splitting. [ABSTRACT FROM AUTHOR]

[Display omitted] • MIL-53(Fe)/metal (Ni, Co, Mn)-phenolic network nanoarchitectures were fabricated for OER. • MIL-53(Fe)/Ni-phenolic network nanoarchitectures revealed the best electrochemical performance due to interface effect. • This work supplied an efficient approach for water splitting. The interface nature of composite catalysts affected drastically the oxygen evolution reaction (OER) behavior. In this paper, nanoarchitecture consisted of Fe-based metal–organic frameworks (MIL-53) and metal-phenolic networks were created. Metal (Mn2+, Co2+, and Ni2+) phenolic networks were assembled on the surface of MIL-53 to form heterostructures. Among them, MIL-53(Fe)/Ni-phenolic network nanoarchitectures revealed the best electrochemical performance. The existence of MIL-53 enhanced the adsorption ability for OH− in the nanoarchitectures. The electron transfer between MIL-53 and Ni-phenolic networks adjusted the filling degree of e g orbitals to optimize the bonding strength between Fe3+/Ni2+ and oxygen intermediate species. MIL-53/Ni-phenolic networks nanoarchitectures exhibited well OER performance with a potential of 282 mV at 10 mA cm−2. This work provided an efficient insight into the structure-properties relation of a promising heterostructure catalyst for water splitting. [ABSTRACT FROM AUTHOR]

The oxygen-evolution reaction (OER) is pivotal in many energy-conversion technologies as it is an important counter reaction to others that convert stable chemicals to higher-value products using electrochemistry. The local microenvironment and pH for the anode OER can vary from acidic to neutral to alkaline depending on the system being explored, making definitive mechanistic insights difficult. In this paper, we couple experiments, first-principles calculations based on density functional theory, microkinetics, and transport modeling to explore the entire pH range of the OER. At low current densities, neutral pH values unexpectedly perform better than the acidic and alkaline conditions, and this trend is reversed at higher current densities (> 20 mA cm−2). Using multiscale modeling, this switch is rationalized by a change from a dual-reaction mechanism to a single rate-determining step. The model also shows how the alkaline reaction rates dominate in the middle to high pH range. Furthermore, we explore that the local pH for near-neutral conditions is much different (e.g., 2.4 at the reaction surface vs. 9 in the bulk) than the pH extremes, demonstrating the criticality that transport phenomena plays in kinetic activity. [ABSTRACT FROM AUTHOR]