Investigation on the reduction of the oxides of Pd and graphite in alkaline medium and the simultaneous evolution of oxygen reduction reaction and peroxide generation features

Effect of H2O2 Concentration on the Electrochemical H2O2 Oxidation and Reduction Reactions on the Pt/C Catalyst in Acid Solutions

Hydrogen peroxide (H2O2) oxidation reaction (HPOR) and reduction reaction (HPRR) play vital roles in various innovative H2O2-related electrochemical energy conversion systems. Understanding the interactions of H2O2 with catalyst surfaces and its impact on HPOR/HPRR activity at the working potential is essential for the further development of these H2O2-related systems. Herein, we investigate the effects of the H2O2 concentration on the HPOR/HPRR activities for Pt/C catalysts and reveal the complex influence of H2O2 on the oxygen coverage of the Pt surface at various potentials. In addition, we find that the apparent number of electrons transferred at the HPRR potential differs from its theoretical value, which is attributed to the release of unreacted hydroxyl radicals via the chemical dissociation of H2O2 at the Pt surface. These findings expand our understanding of the interactions of H2O2 and Pt/C catalysts at the electrochemical interface for HPOR and HPRR, providing valuable insights into the underlying reaction mechanisms.

Research progress of two-dimensional antimonene in energy storage and conversion

Since the first proposal of antimonene in 2015, extensive research attention has been drawn to its application in energy storage and conversion because of its excellent layered structure and fast ion diffusion properties. However, in contrast to the revolutionary expansion of antimonene-based energy devices, reviews on this topic that summarize and further guide the design of 2D antimonene for energy storage and conversion are rare. In this review, the structure, physicochemical properties, and popular synthesis approaches of antimonene are first summarised. Specifically, the rational design and application of antimonene in energy storage and conversion such as electrochemical batteries and supercapacitors, electrocatalytic hydrogen evolution reaction, electrocatalytic oxygen evolution reaction, electrocatalytic carbon dioxide reduction, photocatalytic reduction of organic pollution, photocatalytic reduction of carbon dioxide (CO₂), solar cells and photovoltaic devices are outlined. Finally, opportunities and challenges are presented to further advance the development and application of antimonene in energy conversion and storage.

Heterogeneous assembly of Pt-clusters on hierarchically structured CoOx@SnPd2@SnO2 quaternary nanocatalysts manifesting oxygen reduction reaction performance

Atomic Pt clusters in the heterogeneous interface of CoO_x@SnPd₂@SnO₂ possess high heteroatomic intermixing facilities, oxygen splitting and hydration reactions resulting in high performance ORR.

Alkaline Anion-Exchange Membrane Fuel Cells: Challenges in Electrocatalysis and Interfacial Charge Transfer

Alkaline anion-exchange membrane (AAEM) fuel cells have attracted significant interest in the past decade, thanks to the recent developments in hydroxide-anion conductive membranes. In this article, we compare the performance of current state of the art AAEM fuel cells to proton-exchange membrane (PEM) fuel cells and elucidate the sources of various overpotentials. While the continued development of highly conductive and thermally stable anion-exchange membranes is unambiguously a principal requirement, we attempt to put the focus on the challenges in electrocatalysis and interfacial charge transfer at an alkaline electrode/electrolyte interface. Specifically, a critical analysis presented here details the (i) fundamental causes for higher overpotential in hydrogen oxidation reaction, (ii) mechanistic aspects of oxygen reduction reaction, (iii) carbonate anion poisoning, (iv) unique challenges arising from the specific adsorption of alkaline ionomer cation-exchange head groups on electrocatalysts surfaces, and (v) the potential of alternative small molecule fuel oxidation. This review and analysis encompasses both the precious and nonprecious group metal based electrocatalysts from the perspective of various interfacial charge-transfer phenomena and reaction mechanisms. Finally, a research roadmap for further improvement in AAEM fuel cell performance is delineated here within the purview of electrocatalysis and interfacial charge transfer.

Platinum-trimer decorated cobalt-palladium core-shell nanocatalyst with promising performance for oxygen reduction reaction

Advanced electrocatalysts with low platinum content, high activity and durability for the oxygen reduction reaction can benefit the widespread commercial use of fuel cell technology. Here, we report a platinum-trimer decorated cobalt-palladium core-shell nanocatalyst with a low platinum loading of only 2.4 wt% for the use in alkaline fuel cell cathodes. This ternary catalyst shows a mass activity that is enhanced by a factor of 30.6 relative to a commercial platinum catalyst, which is attributed to the unique charge localization induced by platinum-trimer decoration. The high stability of the decorated trimers endows the catalyst with an outstanding durability, maintaining decent electrocatalytic activity with no degradation for more than 322,000 potential cycles in alkaline electrolyte. These findings are expected to be useful for surface engineering and design of advanced fuel cell catalysts with atomic-scale platinum decoration.

Fuel cells are promising for converting fuel into electricity, but rely on development of high-performance catalysts for oxygen reduction. Here the authors report a highly durable platinum-trimer decorated cobalt-palladium catalyst with low platinum loading for electrocatalysis of oxygen reduction.

Electrochemical estimation of active site density on a metal-free carbon-based catalyst

Nitrogen-doped carbon is synthesized by the heat-treatment of carbon in an ammoniacal atmosphere at different temperatures. The active site density and electrochemically active surface area (ESA) of carbon and nitrogen-doped carbon catalysts are estimated from the charge due to oxidation of the adsorbed anthraquinone-2-sulfonate (AQS) probe molecule. In the potential window of interest and over a range of concentrations, there is no unwanted side reaction or polymerization of the probe molecule that interferes with the electrochemical estimation of active site density. Most importantly, the adsorbed AQS can easily be removed from the electrode surface by potential cycling. The ORR activity and active site density of the catalysts derived from AQS-adsorption have similar trends. The active site density and turnover frequency towards ORR estimated using the AQS-adsorption method are in line with those reported in the literature by other methods. On the other hand, the results show that the wetted surface area estimated from the double layer capacitance does not always correlate with catalytic activity.

Solution-Plasma-Assisted Bimetallic Oxide Alloy Nanoparticles of Pt and Pd Embedded within Two-Dimensional Ti3C2T x Nanosheets as Highly Active Electrocatalysts for Overall Water Splitting

Exploiting high-efficiency and low-cost bifunctional electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) has been actively encouraged because of their potential applications in the field of clean energy. In this paper, we reported a novel electrocatalyst based on an exfoliated two-dimensional (2D) MXene (Ti₃C₂T _x) loaded with bimetallic oxide alloy nanoparticles (NPs) of Pt and Pd (represented by PtO _aPdO _bNPs@Ti₃C₂T _x), which was synthesized via solution plasma (SP) modification. The prepared materials were then utilized as highly efficient bifunctional electrocatalysts toward the HER and OER in alkaline solution. At a high plasma input power (200 W), bimetallic oxide alloy nanoparticles of Pt and Pd or nanoclusters with different metallic valence states were deposited onto the Ti₃C₂T _x nanosheets. Because of the synergism of the noble-metal NPs and the Ti₃C₂T _x nanosheets, the electrocatalytic results revealed that the as-prepared PtO _aPdO _bNPs@Ti₃C₂T _x nanosheets under the plasma input power of 200 W for 3 min only required a low overpotential to attain 10 mA cm^-2 for the HER (-26.5 mV) in 0.5 M H₂SO₄ solution and OER (1.54 V) in 0.1 M KOH solution. Moreover, water electrolysis using this catalyst achieved a water splitting current density of 10 mA cm^-2 at a low cell voltage of 1.53 V in 1.0 M KOH solution. These results suggested that the hybridization of the extremely low usage of PtO _a/PdO _b NPs (1.07 μg cm^-2) and Ti₃C₂T _x nanosheets by SP will expand the applications of other clean energy reactions to achieve sustainable energy.

Electrochemical estimation of the active site density on metal-free nitrogen-doped carbon using catechol as an adsorbate

An electrochemical method to estimate the active site density of metal-free electrocatalysts using catechol adsorption.