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Hydrogen spillover effect has recently garnered a lot of attention in the field of electrocatalytic hydrogen evolution reactions. A new avenue for understanding the dynamic behavior of atomic migration in which hydrogen atoms moving on a catalyst surface was opened up by the setup of the word "hydrogen spillover." However, there is currently a dearth of thorough knowledge regarding the hydrogen spillover effect. Currently, the advancement of sophisticated characterization procedures offers progressively useful information to enhance our grasp of the hydrogen spillover effect. The understanding of material fabrication for hydrogen spillover effect has erupted. Considering these factors, we made an effort to review most of the articles published on the hydrogen spillover effect and carefully analyzed the aspect of material fabrication. All of our attention has been directed toward the molecular pathway that leads to improve hydrogen evolution reactions performance. In addition, we have attempted to elucidate the spillover paths through the utilization of DFT calculations. Furthermore, we provide some preliminary research suggestions and highlight the opportunities and obstacles that are still to be confronted in this study area. [ABSTRACT FROM AUTHOR]

The proton exchange membrane water electrolysis (PEMWE) powered by renewable electricity offers a facile route for clean hydrogen production. The oxygen evolution reaction (OER) at the anode plays a major role in affecting the overall device efficiency due to its sluggish OER kinetics. Thus, it remains a challenge to develop robust and active catalysts for OER in acid media for efficient PEMWE. Currently, iridium (Ir)‐based materials, such as mono‐ and multimetallic Ir, Ir‐based oxides, pyrochlore iridate oxides, and Ir‐based perovskites, are the most promising OER catalysts in acid media for PEMWEs. Extensive research has been conducted to enhance the specific activity of Ir species to make cost‐effective. The present review aims to provide the recent progress on addressing the long‐term durability issue of Ir‐based catalyst for OER in acidic conditions, aspiring to inspire the researchers to design highly efficient and stable Ir‐based catalysts. Moreover, the detailed OER mechanism along with the dissolution nature of Ir species is discussed and summarized. Finally, the status, challenges, and prospects for the development of Ir‐based OER catalysts are discussed. [ABSTRACT FROM AUTHOR]

Exploring bifunctional electrocatalysts to lower the activation energy barriers for sluggish electrochemical reactions for both the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are of great importance in achieving lower energy consumption and higher conversion efficiency for future energy conversion and storage system. Despite the excellent performance of precious metal-based electrocatalysts for OER and ORR, their high cost and scarcity hamper their large-scale industrial application. As alternatives to precious metal-based electrocatalysts, the development of earth-abundant and efficient catalysts with excellent electrocatalytic performance in both the OER and the ORR is urgently required. Herein, we report a core–shell CoFeS2@CoS2 heterostructure entangled with carbon nanotubes as an efficient bifunctional electrocatalyst for both the OER and the ORR. The CoFeS2@CoS2 nanocubes entangled with carbon nanotubes show superior electrochemical performance for both the OER and the ORR: a potential of 1.5 V (vs. RHE) at a current density of 10 mA cm−2 for the OER in alkaline medium and an onset potential of 0.976 V for the ORR. This work suggests a processing methodology for the development of the core–shell heterostructures with enhanced bifunctional performance for both the OER and the ORR. [ABSTRACT FROM AUTHOR]

The development of cost effective and high‐performance electrocatalyst is challenging but essential for realizing industrial hydrogen production by electolyzer. Electrocatalysts for water splitting must have active catalytic performance as well as high stability in strong alkaline or acidic media to be used in commercial elecrolyzer. Transition metal based electrocatalysts are considered as highly promising candidates due to their excellent oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performance and stability with low materials cost. Recently, binder free self‐supported electrocatalysts based on transition metals have emerged as state‐of‐the‐art catalytic electrodes due to their high activity and robustness. These properties are attributed to lack of catalyst powder aggregation and a strong synergetic effect between the electrode surface and catalyst. In this mini review, recent development in self‐supported electrocatalysts for OER, HER and also bifunctional OER & HER are reviewed in terms of superior activity and robust stability. Material design strategies, structural and compositional properties, and catalytic performance of recently reported self‐supported electrocatalysts are summarized. Finally, overview of recent studies, challenges and prospects related to self‐supported electrocatalysts are discussed. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • NiFe alloys derived from Prussian blue analogues (PBAs) were developed as a high-performance electrocatalyst for water oxidation using a facile self-templated synthesis method combined with in-situ O 2 plasma activation process (O-NiFe@C). • O-NiFe@C exhibited substantially low overpotential of 250 and 300 mV for affording water oxidation current densities of 10 and 100 mA cm−2. • Excellent long-term stability longer than 24 h was obtained for O-NiFe@C at high current in alkaline media. Abstract The development of high-performance and robust catalysts with low-cost is the major demand for electrochemical water oxidation. Here, a unique and facile method is reported for the synthesis of NiFe alloy derived from templated Prussian blue analogues (PBAs) on carbon cloth, exhibiting excellent water oxidation activity and stability in alkaline solution. The best water oxidation activity is obtained with O-NiFe@C-600, in which overpotential of 250 mV is required for generating water oxidation current density of 10 mA cm−2 and overpotential of 300 mV was needed for affording 100 mA cm−2. In addition, outstanding long-term stability over 25 h in chronoamperometric measurements was achieved for O-NiFe@C-600. The catalysts considerably outperform the activity and stability of the other PBA derived catalysts and even the noble metal catalysts RuO 2. The excellent performance is attributable to unique self-supported structures of the PBA-derived NiFe catalysts on carbon cloth as well as the incorporation of reactive oxygen species (ROS) by in-situ O 2 plasma activation which further increases the number of active sites for water oxidation. Additionally, well-defined graphitized cells largely enhances stability of the catalyst by acting as chemical protective layers. [ABSTRACT FROM AUTHOR]

The development of bifunctional electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) has recently attracted significant attention. Transition metal-based electrocatalysts have demonstrated a highly promising catalytic performance in electrochemical HER or OER. Moreover, their electrocatalytic performance can be further improved using a self-supported structure of the electrocatalyst, owing to strong physicochemical contact between the catalyst and current collector. In this context, we propose vanadium-incorporated cobalt phosphide (CoVP) self-supported catalysts on carbon cloth (CoVP@CC) as highly efficient bifunctional electrocatalysts for alkaline HER and OER. In CoVP@CC, V plays a crucial role in modulating the surface electronic structure of the self-supported CoP nanosheets, leading to excellent catalytic activity in both HER and OER. The self-supported CoVP@CC demonstrates a promising overall water-splitting performance, requiring only 1.61 V to afford a current density of 10 mA cm−2. • V-incorporated CoP on carbon cloth (CoVP@CC) with a robust self-supported structure is prepared via wet chemistry. • V modulates the surface electronic structure of CoP nanosheets using a high electronic flexibility. • Self-supported CoVP@CC catalysts exhibits excellent catalytic performance for overall water splitting in alkaline media. [ABSTRACT FROM AUTHOR]