Synthesis and Electrochemical Study of Pd-Based Trimetallic Nanoparticles for Enhanced Hydrogen Storage

The success of acceptable hydrogen storage capacities on high surface area carbon materials at ambient temperature requires the combination of both physisorption and chemisorption. Despite the sole reliance on physisorption for hydrogen uptake in carbon, the dispersal of transition metal catalysts on carbon materials significantly enhances hydrogen uptake at ambient temperatures, via the process of hydrogen spillover. In the present study, hydrogen electrosorption onto activated carbon materials modified with different trimetallic dissociation catalysts (Pd–Ag–Cd) was investigated in an acidic medium using cyclic voltammetry and chronoamperometry. A significant synergistic effect on hydrogen storage was observed, which could be attributed to the electrochemical reduction of hydrogen ions initially at the Pd-based nanoparticles and the hydrogen surface diffusion subsequently to the activated carbon. Utilizing electrochemical methods, the optimized composition of the Pd–Ag–Cd alloys was determined to be Pd₈₀Ag₁₀Cd₁₀, with the highest hydrogen sorption capacity at a hydrogen desorption charge of 18.49 C/cm²·mg. With increased kinetics and a decrease in the phase transition, the significant enhancement of hydrogen sorption, in comparison to the Pd–Ag and Pd–Cd bimetallic alloys, was further demonstrated, making Pd–Ag–Cd catalysts attractive for use as hydrogen dissociation catalysts for applications in both hydrogen purification and storage

Facile and Controllable Modification of 3D In₂O₃ Microflowers with In₂S₃ Nanoflakes for Efficient Photocatalytic Degradation of Gaseous <i>ortho</i>-Dichlorobenzene

Novel 3D In₂S₃/In₂O₃ heterostructures comprised of 3D In₂O₃ microflowers and In₂S₃ nanoflakes were synthesized via a facile hydrothermal process followed by an in situ anion exchange reaction. In the In₂S₃/In₂O₃ heterostructures, the In₂S₃ nanoflakes were in situ generated and uniformly assembled on In₂O₃ microflowers. The microstructures, optical properties, oxygen vacancy concentration, and photoreactivity of the heterostructures could be tuned by adjusting the amount of sulfide source. The effect of In₂S₃-nanoflakes modification on the oxygen vacancy concentration, optical properties, charge carrier separation, and charge carrier lifetime of In₂O₃ were investigated systematically. The catalytic activity of the proposed heterostructures for degradation of gaseous <i>ortho</i>-dichlorobenzene (<i>o</i>-DCB, a representative chlorinated volatile organic compounds) was higher than that of either unmodified In₂O₃ or TiO₂ (P25). Meanwhile, oxygen vacancies, systematically explored by Raman, X-ray photoelectron spectroscopy (XPS), and low-temperature electron spin resonance (ESR) spectroscopy, were demonstrated to have a two-side effect on the photocatalytic performance. Particularly, the main reaction products including <i>o</i>-benzoquinone type species, phenolate species, formates, acetates, and maleates were verified with in situ FTIR spectroscopy. Additionally, ESR examination confirmed that ^•OH and ^•O₂^– were the predominant reactive oxygen species involved in the degradation of gaseous <i>o</i>-DCB. The current research provides new insight into utilizing In-based heterostructures as promising and efficient visible-spectrum-responsive catalysts for the removal of harmful chlorinated volatile organic compounds

Superb Pseudocapacitance Based on Three-Dimensional Porous Nickel Oxide Modified with Iridium Oxide

The need for environmentally compatible, less polluting, and more efficient energy systems has spurred extensive research into the development of batteries and other energy storage devices. Here, we report on a novel three-dimensional (3D) porous nickel modified with iridium oxide (IrO₂) toward the design of a high-performance pseudocapacitor. The 3D porous nickel is grown directly onto a Ni plate via a facile electrochemical deposition method assisted by the simultaneously formed hydrogen bubble template. The effects of the electrodeposition time and the current density are systemically investigated, revealing that 3.0 A cm^–2 and 150 s are the optimal conditions for the growth of the 3D porous nickel with the highest active surface area, which is subsequently modified with different quantities of IrO₂. The electrodeposited 3D porous Ni network structure serves as a suitable template to accommodate the cast iridium chloride precursor and to anchor the formed IrO₂ during the subsequent thermal treatment. The formed 3D porous NiIr(10%)­Ox electrode exhibits high charge/discharge stability and a superb specific capacitance 1643 F g^–1 at 1.92 A g^–1, which is ∼175 times higher than the 3D porous NiO and over 95 times higher than the same amount of IrO₂ deposited on a smooth Ni substrate

Sensitive Electrochemical Detection of Nitric Oxide Release from Cardiac and Cancer Cells via a Hierarchical Nanoporous Gold Microelectrode

The importance of nitric oxide (NO) in many biological processes has garnered increasing research interest in the design and development of efficient technologies for the sensitive detection of NO. Here we report on a novel gold microelectrode with a unique three-dimensional (3D) hierarchical nanoporous structure for the electrochemical sensing of NO, which was fabricated via a facile electrochemical alloying/dealloying method. Following the treatment, the electrochemically active surface area (ECSA) of the gold microelectrode was significantly increased by 22.9 times. The hierarchical nanoporous gold (HNG) microelectrode exhibited excellent performance for the detection of NO with high stability. On the basis of differential pulse voltammetry (DPV) and amperometric techniques, the obtained sensitivities were 21.8 and 14.4 μA μM^–1 cm^–2, with detection limits of 18.1 ± 1.22 and 1.38 ± 0.139 nM, respectively. The optimized HNG microelectrode was further utilized to monitor the release of NO from different cells, realizing a significant differential amount of NO generated from the normal and stressed rat cardiac cells as well as from the untreated and treated breast cancer cells. The HNG microelectrode developed in the present study may provide an effective platform in monitoring NO in biological processes and would have a great potential in the medical diagnostics

Electrochemical Reduction of Carbon Dioxide at TiO₂/Au Nanocomposites

Herein, we report on the facile synthesis of nanocomposite consisting of TiO2 and Au nanoparticles (NPs) via a tailored galvanic replacement reaction (GRR). The electrocatalytic activity of the synthesized TiO2/Au nanocomposites for CO2 reduction was investigated in an aqueous solution using various electrochemical methods. Our results demonstrated that the TiO2/Au nanocomposites formed through the GRR process exhibited improved catalytic activities for CO2 reduction, while generating more hydrocarbon molecules than the typical formation of CO in contrast to polycrystalline Au. GC analysis and NMR spectroscopy revealed that CO and CH4 were the gas products, whereas HCOO–, CH3COO–, CH3OH, and CH3CH2OH were the liquid products from the CO2 reduction at different cathodic potentials. This remarkable change was further studied using the density functional theory (DFT) calculations, showing that the TiO2/Au nanocomposites may increase the binding energy of the formed ·CO intermediate and reduce the free energy compared to Au, thus favoring the downstream generation of multicarbon products. The TiO2/Au nanocomposites have high catalytic activity and excellent stability and are easy to fabricate, indicating that the developed catalyst has potential application in the electrochemical reduction of CO2 to value-added products