Unveiling the Dynamic Electrocatalytic Activity of Online Synthesized Bimetallic Nanocatalysts via Electrochemiluminescence Microscopy

Effective bimetallic nanoelectrocatalysis demands precise control of composition, structure, and understanding catalytic mechanisms. To address these challenges, we employ a two-in-one approach, integrating online synthesis with real-time imaging of bimetallic Au@Metal core-shell nanoparticles (Au@M NPs) via electrochemiluminescence microscopy (ECLM). Within 120 s, online electrodeposition and in situ catalytic activity screening alternate. ECLM captures transient faradaic processes during potential switches, visualizes electrochemical processes in real-time, and tracks catalytic activity dynamics at the single-particle level. Analysis using ECL photon flux density eliminates size effects and yields quantitative electrocatalytic activity results. Notably, a nonlinear activity trend corresponding to the shell metal to Au surface atomic ratio is discerned, quantifying the optimal surface component ratio of Au@M NPs. This approach offers a comprehensive understanding of catalytic behavior during the deposition process with high spatiotemporal resolution, which is crucial for tailoring efficient bimetallic nanocatalysts for diverse applications.

Study on free and entangled binary metal nanocatalysts for removal of 2,4,6-trichlorophenol in aqueous phase: a comparative study

The present study highlights the comparative catalytic removal of 2,4,6-trichlorophenol (TCP) in the aqueous phase by binary nanoparticles in free as well as entangled forms. In brief, binary nanoparticles comprising Fe-Ni are prepared, characterized, and subsequently entangled in reduced graphene oxide (rGO) for better performances. Optimization studies on the mass of free and rGO-entangled binary nanoparticles with respect to TCP concentration and other environmental factors were carried out. Results suggested that free binary nanoparticles at 40 mg ml^-1took 300 min to dechlorinate 600 ppm of TCP, whereas rGO-entangled Fe-Ni particles at the same mass took only 190 min to dechlorinate when the pH was maintained at near neutral. In addition, experiments on the reuse of the catalyst with respect to removal efficiency were carried out, and the results implied that, compared to free form, rGO-entangled nanoparticles exemplify more than 98% of removal efficacy even after 5 times of exposure to 600 ppm TCP concentration. The reduction in percentage removal was observed after the sixth exposure. A sequential dechlorination pattern was assessed and confirmed using high-performance liquid chromatography. Further, the phenol-enriched aqueous phase is exposed toBacillus licheniformisSL10, which degrades the phenol effectively within 24 h. In conclusion, the prepared binary nanoparticles, both in free as well as in rGO-entangled forms, effectively dechlorinate 2,4,6-TCP contaminations in the aqueous phase, but with differences in removal duration. Entanglement also makes it easier to reuse the catalyst. Furthermore, microbial phenol degradation allows the aqueous phase to be free of 2, 4, and 6-TCP contamination and allows for the reuse of treated water.

Bimetallic Nanocatalysts Immobilized in Nanoporous Hydrogels for Long-Term Robust Continuous Glucose Monitoring of Smart Contact Lens

Smart contact lenses for continuous glucose monitoring (CGM) have great potential for huge clinical impact. To date, their development has been limited by challenges in accurate detection of glucose without hysteresis for tear glucose monitoring to track the blood glucose levels. Here, long-term robust CGM in diabetic rabbits is demonstrated by using bimetallic nanocatalysts immobilized in nanoporous hydrogels in smart contact lenses. After redox reaction of glucose oxidase, the nanocatalysts facilitate rapid decomposition of hydrogen peroxide and nanoparticle-mediated charge transfer with drastically improved diffusion via rapid swelling of nanoporous hydrogels. The ocular glucose sensors result in high sensitivity, fast response time, low detection limit, low hysteresis, and rapid sensor warming-up time. In diabetic rabbits, smart contact lens can detect tear glucose levels consistent with blood glucose levels measured by a glucometer and a CGM device, reflecting rapid concentration changes without hysteresis. The CGM in a human demonstrates the feasibility of smart contact lenses for further clinical applications.

Formation and Functioning of Bimetallic Nanocatalysts: The Power of X-ray Probes

Bimetallic nanocatalysts are key enablers of current chemical technologies, including car exhaust converters and fuel cells, and play a crucial role in industry to promote a wide range of chemical reactions. However, owing to significant characterization challenges, insights in the dynamic phenomena that shape and change the working state of the catalyst await further refinement. Herein, we discuss the atomic-scale processes leading to mono- and bimetallic nanoparticle formation and highlight the dynamics and kinetics of lifetime changes in bimetallic catalysts with showcase examples for Pt-based systems. We discuss how in situ and operando X-ray spectroscopy, scattering, and diffraction can be used as a complementary toolbox to interrogate the working principles of today's and tomorrow's bimetallic nanocatalysts.

Copper⁻Silver Bimetallic Nanowire Arrays for Electrochemical Reduction of Carbon Dioxide

The electrochemical conversion of carbon dioxide (CO₂) into gaseous or liquid fuels has the potential to store renewable energies and reduce carbon emissions. Here, we report a three-step synthesis using Cu⁻Ag bimetallic nanowire arrays as catalysts for electrochemical reduction of CO₂. CuO/Cu₂O nanowires were first grown by thermal oxidation of copper mesh in ambient air and then reduced by annealing in the presence of hydrogen to form Cu nanowires. Cu⁻Ag bimetallic nanowires were then produced via galvanic replacement between Cu nanowires and the Ag⁺ precursor. The Cu⁻Ag nanowires showed enhanced catalytic performance over Cu nanowires for electrochemical reduction of CO₂, which could be ascribed to the incorporation of Ag into Cu nanowires leading to suppression of hydrogen evolution. Our work provides a method for tuning the selectivity of copper nanocatalysts for CO₂ reduction by controlling their composition.