Electrochemical glycerol oxidation reaction (GOR) is an attractive alternative anodic reaction to oxygen evolution reaction for a variety of electrolytic synthesis, thanks to the possibility of mass production of glycerol from biomass and the relative low thermodynamic potential of GOR. The development of high-activity cheap electrocatalysts toward GOR yet faces a daunting challenge. Herein, we experimentally prepare a new range of high entropy alloy (HEA) self-supported electrodes with uniform HEA nanoparticles grown on carbon cloth. The systematic electrochemical studies verify that the HEA-CoNiCuMnMo electrode exhibits attractive performance for GOR electrocatalysis with low overpotential and high selectivity toward formate products. The surface atomic configurations of HEA-CoNiCuMnMo are studied by a self-developed machine learning-based Monte Carlo simulation, which points out the catalytic active center to be Mo sites coordinated by Mn, Mo, and Ni. We further develop a hybrid alkali/acid flow electrolytic cell by pairing alkaline GOR with acidic hydrogen evolution reaction using the HEA-CoNiCuMnMo and the commercial RhIr/Ti as the anode and the cathode, respectively, which only requires an applied voltage of 0.55 V to reach an electrolytic current density of 10 mA cm-2 and maintains long-term electrolysis stability over 12 days continuous running at 50 mA cm-2 with Faraday efficiencies of over 99% for H2 in the cathode and 92% for formate production in the anode.

High Entropy Alloy Electrocatalytic Electrode toward Alkaline Glycerol Valorization Coupling with Acidic Hydrogen Production.

The creation of high-performing, robust bifunctional electrocatalysts for both cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER) in water-splitting is crucial for producing emerging hydrogen economy. Here we report a high entropy alloy (HEA) – FeCoNiCuPd – thin film catalyst, which demonstrated excellent alkaline HER and OER performance with ultralow overpotentials as low as 29 mV for HER and 194 mV for OER at a current density of 10 mA cm− 2. The outstanding catalytic activity for HER was found to originate from the multiple active sites present on the FeCoNiCuPd surface, while for OER it came from the highly functional (FeCoNi)-oxyhydroxide species formed on the film surface. Moreover, the two-electrode electrolyzer made of the FeCoNiCuPd film electrodes required a low cell voltage of 1.52 V to achieve 10 mA cm−2 in 1.0 M KOH, greatly outperforming commercially available Pt/C||RuO2 electrodes, while maintaining a notable durability. This work demonstrated the remarkable potential of a HEA thin film in catalyzing water-splitting process. 

Efficient FeCoNiCuPd thin-film electrocatalyst for alkaline oxygen and hydrogen evolution reactions

Ternary noble metal-semiconductor nanocomposites (NCs) with core-shell-satellite nanostructures have received widespread attention due to their outstanding performance in detecting pollutants through surface-enhanced Raman scattering (SERS) and photodegradation of organic pollutants. In this work, ternary Au@Cu2O-Ag NCs were designed and prepared by a galvanic replacement method. The effect of different amounts of Ag nanocrystals adsorbed on the surfaces of Au@Cu2O on the SERS activity was investigated based on the SERS detection of 4-mercaptobenzoic acid (4-MBA) reporter molecules. Based on electromagnetic field simulations and photoluminescence (PL) results, a possible SERS enhancement mechanism was proposed and discussed. Moreover, Au@Cu2O-Ag NCs served as SERS substrates, and highly sensitive SERS detection of malachite green (MG) with a detection limit as low as 10-9 M was achieved. In addition, Au@Cu2O-Ag NCs were recycled due to their superior self-cleaning ability and could catalyze the degradation of MG driven by visible light. This work demonstrates a wide range of possibilities for the integration of recyclable SERS detection and photodegradation of organic dyes and promotes the development of green testing techniques.

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Self-sustainable and recyclable ternary Au@Cu2O-Ag nanocomposites: application in ultrasensitive SERS detection and highly efficient photocatalysis of organic dyes under visible light.

High entropy alloy/C nanoparticles derived from polymetallic MOF as promising electrocatalysts for alkaline oxygen evolution reaction

Green hydrogen production by renewables-powered water electrolysis holds the key to energy sustainability and a carbon-neutral future. The sluggish kinetics of water-splitting reactions, namely, hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), however, remains a bottleneck to the water electrolysis technology. High-entropy materials, due to their compositional flexibility, structural stability, and synergy between various elemental components, have recently aroused considerable interest in catalyzing the water-splitting reactions. Herein, a timely review of the recent achievements is provided in high-entropy materials for water electrolysis. An overview of different kinds of high-entropy materials for catalyzing the HER and OER half-reactions is introduced, followed by a discussion of theoretical and experimental efforts in understanding the fundamental origins of the enhanced catalytic performance observed on high-entropy catalysts. Various materials design strategies, including control of size and shape, construction of a porous structure, engineering of defect, and formation of hybrid/composite structure, to develop high-entropy catalysts with improved catalytic performance are highlighted. Finally, the remaining challenges are pointed out and the corresponding perspectives to address these challenges are put forward to promote the development of the research field of high-entropy water-splitting catalysts. 

High‐Entropy Materials for Water Electrolysis

Advanced materials for electrocatalytic water splitting applications have been sought-after considering both environmental and economic requirements. However, the traditional materials design concept limits the exploration of high-performance catalysts. The born of a materials design concept based on multiple elements, high-entropy materials, provides a promising path to break the shackles of compositional design in materials science. A number of high-entropy materials were reported to show remarkable properties for electrocatalytic water splitting applications. High-entropy materials were widely confirmed to be one kind of the best electrocatalysts for water splitting applications. Due to the synergy of multiple metal components, they show excellent catalytic activity. Several nontraditional methods were developed and reported to prepare high-performance high-entropy materials. This review article presents the recent progress on high-entropy materials for electrocatalytic water splitting applications. Moreover, it presents the research interests and future prospects in this field.

Shiqi Wang

Papers

Efficient FeCoNiCuPd thin-film electrocatalyst for alkaline oxygen and hydrogen evolution reactions

High entropy alloy/C nanoparticles derived from polymetallic MOF as promising electrocatalysts for alkaline oxygen evolution reaction

Recent progress on high-entropy materials for electrocatalytic water splitting applications

Preferentially oriented Ag-TiO2 nanotube array film: An efficient visible-light-driven photocatalyst.

Single-crystal-like black Zr-TiO2 nanotube array film: An efficient photocatalyst for fast reduction of Cr(VI)