Activity-Drop of Hydrogen Evolution Reaction in LiNO Based "Hydronium-in-Salt" Acidic Electrolytes on Platinum Enables Electrochemical Nitrate Reduction.

The electrochemical nitrate reduction reaction (NORR) involves multiple hydrogenation and deoxygenation steps, which compete with the hydrogen evolution reaction (HER). Therefore, NORR driven in acidic media is challenging in spite of advantageous fast hydrogen transfers in its elementary steps. The findings presented in this article first demonstrate that the NORR is significantly activated even in acidic lithium nitrate solutions at LiNO concentrations exceeding 6 m on a Pt electrode (the highly effective catalyst for HER) by the formation of a "hydronium-in-salt" electrolyte (HISE), a new type of aqueous high concentration salt electrolyte.

Thermomechanical and Structural Analysis of WO Array for Optimized Photoelectrochemical Chloride Oxidation Performance.

Understanding the crystal structure of WO is essential for optimizing its photoelectrochemical performance. This study comprehensively analyzes the structural characteristics of WO during synthesis and investigates their correlation with photoelectrochemical activity. Structural analysis, incorporating annealing procedure and WO thickness, identifies a blend of hexagonal, monoclinic, and orthorhombic phases within WO array.

Unlocking the Potential of BiS-Derived Bi Nanoplates: Enhanced Catalytic Activity and Selectivity in Electrochemical and Photoelectrochemical CO Reduction to Formate.

Various electrocatalysts are extensively examined for their ability to selectively produce desired products by electrochemical CO reduction reaction (CORR). However, an efficient CORR electrocatalyst doesn't ensure an effective co-catalyst on the semiconductor surface for photoelectrochemical CORR. Herein, BiS nanorods are synthesized and electrochemically reduced to Bi nanoplates that adhere to the substrates for application in the electrochemical and photoelectrochemical CORR.

Redox-Transition from Irreversible to Reversible Vitamin C by Pore Confinement in Microporous Carbon Network.

Enhancement of redox-reversibility in electroactive species has been studied because of fundamental interest and their importance for energy storage systems. Various electroactive molecules suffer from redox-irreversible behavior, and this is a critical reason for their exclusion as redox electrolytes in energy storage systems. In this article, we fully demonstrated that ascorbic acid (ASC), which is an abundant but redox-irreversible molecule, can become redox-reversible when it is confined in microporous carbon regimes.

Unraveling the Simultaneous Enhancement of Selectivity and Durability on Single-Crystalline Gold Particles for Electrochemical CO Reduction.

Electrochemical carbon dioxide reduction is a mild and eco-friendly approach for CO mitigation and producing value-added products. For selective electrochemical CO reduction, single-crystalline Au particles (octahedron, truncated-octahedron, and sphere) are synthesized by consecutive growth and chemical etching using a polydiallyldimethylammonium chloride (polyDDA) surfactant, and are surface-functionalized. Monodisperse, single-crystalline Au nanoparticles provide an ideal platform for evaluating the Au surface as a CO reduction catalyst.

Heterointerface Effect on Two-Step Nucleation Mechanism of Bi Particles.

The nucleation and crystallization of Bi particles on two matrices, crystalline bismuth sulfide (-BiS) and amorphized bismuth titanium oxide (-BiTiO), were studied by using in situ transmission electron microscopy (TEM) analysis. The atomic structures of the Bi particles were monitored by acquiring high-resolution TEM images in real time. The Bi particles were grown on -BiS and -BiTiO via a two-step nucleation mechanism; dense liquid clusters were clearly observed at the initial stage of nucleation, and the coalescence of clusters was frequently observed during the growth.

Electrochemical Generation of Mesopores and Residual Oxygen for the Enhanced Activity of Silver Electrocatalysts.

The development of stable and efficient electrocatalysts is of key importance for the establishment of a sustainable society. The activity of a metal electrocatalyst is determined by its electrochemically active surface area and intrinsic activity, which can be increased using highly porous structures and heteroatomic doping, respectively. Herein, we propose a general strategy of generating mesopores and residual oxygen in metal electrocatalysts by reduction of metastable metal oxides using AgO electrodeposited onto carbon paper as a model system and demonstrating that the obtained multipurpose porous Ag electrocatalyst has high activity for the electroreduction of O and CO.

Accelerated decomposition of BiS nanorods in water under an electron beam: a liquid phase transmission electron microscopy study.

Evaluating the stability of semiconductor photocatalysts is critical in the development of efficient catalysts. The morphological and microstructural behaviors of nanorod-shaped BiS semiconductors in aqueous solution were studied using a liquid cell transmission electron microscopy (TEM) technique. The rapid decomposition of BiS in water was observed under electron beam irradiation during TEM.

Understanding and Improving Photocatalytic Activity of Pd-Loaded BiVO Microspheres: Application to Visible Light-Induced Suzuki-Miyaura Coupling Reaction.

The effective utilization of visible light is required for exploiting photocatalytic reactions in indoor and outdoor environments. In this study, Pd-supported BiVO microspheres (Pd-BiVO) were prepared for visible light-induced photocatalytic reactions. Under irradiation with a white light-emitting diode, the obtained Pd-BiVO composite exhibited considerably improved catalytic activity for the decomposition of an organic dye compared with other BiVO catalysts.

Comprehensive Study of the Growth Mechanism and Photoelectrochemical Activity of a BiVO/BiS Nanowire Composite.

A BiVO/BiS composite comprising BiS nanowires on top of a BiVO film was prepared via hydrothermal reaction. Because additional Bi ions were not delivered during the reaction, BiVO served as the Bi ion source for the development of BiS. A detailed growth mechanism of the nanowire was elucidated by an analysis of the concentration gradient of Bi and S ions during the reaction.

Current research on single-entity electrochemistry for soft nanoparticle detection: Introduction to detection methods and applications.

In recent years, rapid progress in the field of single-entity electrochemistry (SEE) has opened a novel exploratory area in the field of analytical and electrochemistry. SEE is a method of studying the behavior of particles at the single particle level, which yields important information on the diffusion coefficient, individual particle size, size distribution, catalytic activity, collision frequency, and internal substances of the particles. Various types of particles have been studied through SEE.

In Situ Growth of the BiS Nanowire Array on the BiMoO Film for an Improved Photoelectrochemical Performance.

A single-crystalline BiS nanowire array (BiSNWA) is synthesized by an in situ hydrothermal reaction on the surface of a BiMoO film. As no additional source of Bi is provided during the process, the BiMoO layer acts as the Bi source for the synthesis of BiS nanowires. The fabricated BiMoO/BiSNWA electrode exhibited an increased photoelectrochemical (PEC) sulfite oxidation activity, which is attributed mainly to the effective interface obtained by the in situ hydrothermal growth, compared to other BiS electrodes.

Understanding Reaction Kinetics by Tailoring Metal Co-catalysts of the BiVO Photocatalyst.

In this study, the reaction mechanisms of metal-semiconductor composites used as photocatalysts were demonstrated by first preparing bismuth vanadate (BiVO) and then performing photodeposition of metal nanoparticles. The photocatalytic activity of metal-BiVO (M-BiVO, where M = Pt, Au, Ag) composites were evaluated through dye decomposition under UV-vis irradiation. The photocatalytic efficiency was significantly enhanced after Pt deposition as compared to other M-BiVO composites.

Understanding metal-enhanced fluorescence and structural properties in Au@Ag core-shell nanocubes.

Au@Ag core-shell structures have received particular interest due to their localized surface plasmon resonance properties and great potential as oxygen reduction reaction catalysts and building blocks for self-assembly. In this study, Au@Ag core-shell nanocubes (Au@AgNCs) were fabricated in a facile manner stepwise Ag reduction on Au nanoparticles (AuNPs). The size of the Au@AgNCs and their optical properties can be simply modulated by changing the Ag shell thickness.

Facile Synthesis of BiVO for Visible-Light-Induced C-C Bond Cleavage of Alkenes to Generate Carbonyls.

BiVO crystals synthesized by an ultrasonic-assisted method (Sono-BiVO ) showed improved efficiency as a heterogeneous photocatalyst under visible-light irradiation. Sono-BiVO was successfully used for the C-C bond cleavage of alkenes to generate carbonyl compounds. Styrene derivatives were converted into carbonyl compounds in the presence of Sono-BiVO under highly sustainable conditions requiring only natural sources, that is, molecular oxygen, visible light, and water at room temperature.

Ultrasonic-assisted preparation of a pinhole-free BiVO photoanode for enhanced photoelectrochemical water oxidation.

A pinhole-free BiVO4 electrode was successfully synthesized using an ultrasonic-assisted synthetic method on a conductive substrate. The pinhole-free BiVO4 electrode showed highly improved photoelectrochemical activity for both sulfite oxidation and water oxidation. The blocking recombination processes were examined to clarify the enhanced photoelectrochemical performances.

Synthesis of Hollow Iron Oxide Nanospheres and Their Application to Gas Sensors.

Hollow nanomaterials have attracted great interest because of their many applications in catalysis, nanoreactors, drug delivery systems, for lubrication and in gas sensors. Here, carbon sphere templates were prepared from glucose under hydrothermal conditions to facilitate the synthesis of hollow Fe2O3 nanospheres. Thermal decomposition of an iron precursor in benzylalcohol with the carbon spheres resulted in the deposition of Fe3O4 nanoparticles on the carbon sphere templates.

Highly stable mesoporous silica nanospheres embedded with FeCo/graphitic shell nanocrystals as magnetically recyclable multifunctional adsorbents for wastewater treatment.

Highly stable and magnetically separable mesoporous silica nanospheres (MSNs) embedded with 4.6 ± 0.8 nm FeCo/graphitic carbon shell nanocrystals (FeCo/GC NCs@MSNs) were synthesized by thermal decomposition of metal precursors in MSNs and subsequent methane CVD.

Colloidal zinc oxide-copper(I) oxide nanocatalysts for selective aqueous photocatalytic carbon dioxide conversion into methane.

Developing catalytic systems with high efficiency and selectivity is a fundamental issue for photochemical carbon dioxide conversion. In particular, rigorous control of the structure and morphology of photocatalysts is decisive for catalytic performance. Here, we report the synthesis of zinc oxide-copper(I) oxide hybrid nanoparticles as colloidal forms bearing copper(I) oxide nanocubes bound to zinc oxide spherical cores.

Engineering Reaction Kinetics by Tailoring the Metal Tips of Metal-Semiconductor Nanodumbbells.

Semiconductor-metal hybrid nanostructures are one of the best model catalysts for understanding photocatalytic hydrogen generation. To investigate the optimal structure of metal cocatalysts, metal-CdSe-metal nanodumbbells were synthesized with three distinct sets of metal tips, Pt-CdSe-Pt, Au-CdSe-Au, and Au-CdSe-Pt. Photoelectrochemical responses and transient absorption spectra showed that the competition between the charge recombination at the metal-CdSe interface and the water reduction on the metal surface is a detrimental factor for the apparent hydrogen evolution rate.

Shape-controlled Pt nanocubes directly grown on carbon supports and their electrocatalytic activity toward methanol oxidation.

Synthesis of shape-controlled Pt nanocrystals is substantial and important for enhancing chemical and electrochemical reactions. However, the removal of capping agents, shape-controlling chemicals, on Pt surfaces is essential prior to conducting the catalytic reactions. Here we report a facile one-pot synthesis of Pt nanocubes directly grown on carbon supports (Pt nanocubes/C) with modulating the kinetic reaction factors for shaping the nanocrystals, but without adding any capping agents for preserving the clean Pt surfaces.

Spontaneous phase transition of hexagonal wurtzite CoO: application to electrochemical and photoelectrochemical water splitting.

The addition of water initiates the phase transition of hexagonal CoO to Co(OH) nanocrystals. Inducing the phase transition of h-CoO on various substrates results in efficient chemical bonding between Co(OH) and the substrate. The efficient deposition of Co(OH) is widely applicable for electrochemical and photoelectrochemical water oxidation reactions.

Preparation and phase transition of FeOOH nanorods: strain effects on catalytic water oxidation.

The evolution of the phase and morphology of FeOOH nanorods prepared by a hydrothermal method is studied via X-ray diffraction (XRD) and in situ transmission electron microscopy. The FeOOH nanorod with a tetragonal structure (β-FeOOH) is gradually converted into a rhombohedral FeO nanorod by a simple thermal treatment. The existence of an intermediate FeOOH structure with high lattice strains during the phase transition is identified by Rietveld analysis using XRD.

A self-assembled Ni(cyclam)-BTC network on ITO for an oxygen evolution catalyst in alkaline solution.

A self-assembled Ni(cyclam)-BTC film was formed on ITO in an acidic solution. Ni(cyclam)-BTC exhibited an enhanced electro-catalytic property for the oxygen evolution reaction (OER), which was strongly relevant to the Ni(iii)/Ni(iv) redox reaction activated by the potential dynamic process. A possible formation mechanism of Ni(cyclam)-BTC by self-assembly on ITO was also proposed.

Controlled Synthesis of Hollow Manganese Oxide Nanocrystals.

Carbon spheres have been prepared from glucose under hydrothermal conditions to facilitate the synthesis of hollow manganese oxides. The phases of manganese oxide are controlled by changing annealing temperature of the manganese monoxide on a carbon sphere template. The particles on the carbon surface get an agglomeration and make dense oxide shell during the calcination step, which result in typical hollow structures.