Search for: All records

Abstract Development of high‐performance, low‐cost catalysts for electrochemical water splitting is key to sustainable hydrogen production. Herein, ultrafast synthesis of carbon‐supported ruthenium–copper (RuCu/C) nanocomposites is reported by magnetic induction heating, where the rapid Joule's heating of RuCl₃and CuCl₂at 200 A for 10 s produces Ru–Cl residues‐decorated Ru nanocrystals dispersed on a CuCl_xscaffold, featuring effective Ru to Cu charge transfer. Among the series, the RuCu/C‐3 sample exhibits the best activity in 1 mKOH toward both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), with an overpotential of only −23 and +270 mV to reach 10 mA cm⁻², respectively. When RuCu/C‐3 is used as bifunctional catalysts for electrochemical water splitting, a low cell voltage of 1.53 V is needed to produce 10 mA cm⁻², markedly better than that with a mixture of commercial Pt/C+RuO₂(1.59 V). In situ X‐ray absorption spectroscopy measurements show that the bifunctional activity is due to reduction of the Ru–Cl residues at low electrode potentials that enriches metallic Ru and oxidation at high electrode potentials that facilitates the formation of amorphous RuO_x. These findings highlight the unique potential of MIH in the ultrafast synthesis of high‐performance catalysts for electrochemical water splitting. 

Abstract Ruthenium has been hailed as a competitive alternative for platinum toward hydrogen evolution reaction (HER), a critical process in electrochemical water splitting. In this study, we successfully prepare metallic Ru nanoparticles supported on carbon paper by utilizing a novel magnetic induction heating (MIH) method. The samples are obtained within seconds, featuring a Cl‐enriched surface that is unattainable via conventional thermal annealing. The best sample within the series shows a remarkable HER activity in both acidic and alkaline media with an overpotential of only ‐23 and ‐12 mV to reach the current density of 10 mA/cm², highly comparable to that of the Pt/C benchmark. Theoretical studies based on density functional theory show that the excellent electrocatalytic activity is accounted by the surface metal‐Cl species that facilitate charge transfer and downshift the d‐band center. Results from this study highlight the unique advantages of MIH in rapid sample preparation, where residual anion ligands play a critical role in manipulating the electronic properties of the metal surfaces and the eventual electrocatalytic activity. 

Abstract Vertically oriented graphene (VG) nanosheets exhibit unique structural characteristics, such as large accessible surface area, rich edges, high electrical conductivity, open network channels, and agglomeration resistance, for electrochemical energy‐storage applications (e. g., supercapacitors, lithium‐ion batteries, etc.). In this Review article, we summarize recent progress in the design and engineering of VG‐based electrodes for high‐performance electrochemical energy technologies within the context of energy‐storage mechanisms and charge‐transfer kinetics, and include a perspective to highlight the challenges and promises in the exploitation of vertically oriented two‐dimensional carbon nanostructures for further enhancement of the performance of electrochemical energy‐storage devices. 

Abstract Single‐atom catalysts (SACs) have been attracting extensive interest in the electrocatalytic production of hydrogen peroxide by oxygen reduction reaction (ORR). This is due to the maximal efficiency of atom utilization and intimate interaction of the metal centers with the supporting matrix that may be exploited for deliberate manipulation of the electrocatalytic activity and selectivity, in comparison with the conventional nanoparticle counterparts. Herein, we summarize recent progress of the design and engineering of SACs towards ORR for H₂O₂generation, based on both noble and non‐noble metals. We conclude the review with a perspective highlighting the promises and challenges involved in future research. 

Abstract Developing high performance nonprecious metal‐based electrocatalysts has become a critical first step towards commercial applications of metal‐air batteries. Herein, nanocomposites based on Co/Co₂P nanoparticles encapsulated within hierarchically porous N, P, S co‐doped carbon are prepared by controlled pyrolysis of zeolitic imidazolate frameworks (ZIF‐67) and poly(cyclotriphosphazene‐co‐4,4’‐sulfonyldiphenol) (PZS). The resulting Co/Co₂P@NPSC nanocomposites exhibit apparent oxygen reduction reaction (ORR) and evolution reaction (OER) catalytic performance, and are used as the reversible oxygen catalyst for zinc‐air batteries (ZABs). Density functional theory (DFT) calculations exhibit that Co₂P could provide active sites for the ORR and promote the conversion between the adsorbed intermediates, and porous N,P,S co‐doped carbon with Co₂P nanoparticles also improves the exposure of actives sites and endows charge transport. Liquid‐state ZABs with Co/Co₂P@NPSC as the cathode catalysts demonstrate the greater power density of 198.1 mW cm⁻²and a long cycling life of 50 h at 10 mA cm⁻², likely due to the encapsulation of Co/Co₂P nanoparticles by the carbon shell. Solid‐state ZABs also display a remarkable performance with a high peak power density of 74.3 mW cm⁻². Therefore, this study indicates the meaning of the design and engineering of hierarchical porous carbon nanomaterial as electrocatalyst for rechargeable metal‐air batteries. 

Synergetic interactions between ruthenium and molybdenum oxide weaken H adsorption on ruthenium active sites and hence enhance the electrocatalytic activity towards hydrogen evolution reaction.