Chunlai Wang

Pristine metal–organic frameworks (MOFs) generally suffer from low mechanical strength and poor processability, hindering their direct application in fixed-bed adsorption systems. In this work, we propose a stepwise impregnation strategy that enables uniform in-situ crystallization of UTSA-16(Co) within amino-functionalized polyacrylate (PAA-NH₂) matrices via pre-anchored cobalt ion sites, designed to overcome the low loading and inhomogeneous distribution issues of conventional one-step impregnation methods. Three synthesis protocols (one-step impregnation, stepwise impregnation, and secondary growth) were systematically compared, and the stepwise approach achieved the highest MOF loading of 53 wt%. The optimal composite exhibited a thermogravimetric (TGA) pure-CO₂ uptake of 95.0 mg/g at 25 °C and 1 bar and retained 98.6% of its initial capacity after 10 consecutive adsorption–desorption cycles, indicating good short-term cyclic stability. Systematic fixed-bed tests revealed that the empirical Avrami fractional-order model (R² ≥ 0.994) accurately described the heterogeneous adsorption kinetics of the composite, and the dynamic breakthrough behavior was jointly regulated by gas flow rate, bed temperature, inlet CO₂ concentration, and relative humidity. The composite was found to be moisture-sensitive: at 60% RH, the capacity fell by 52.6%. A desorption efficiency above 99% was achieved within 20 min under optimal conditions (90 °C, 0.6 L/min purge gas). Overall, this work provides systematic kinetic data and operational guidelines for the optimization of MOF–polymer composite adsorbents in laboratory-scale fixed-bed applications.

The Ag/carbon dots (CDs)/TiO ₂ nanotube array (TNTA) composite material, comprising silver nanoparticles (AgNPs), CDs, and TNTA, was synthesized via a one-step solvothermal method to enhance photocatalytic activity. The composite photocatalyst was employed as a bacteriostatic agent against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa under various light conditions using the inhibition zone and colony counting experiments. The photocatalytic antibacterial mechanism of Ag/CDs/TNTA was also investigated. The composite material effectively facilitates the transfer of photogenerated electrons and increases photocatalytic activity, and adjusts the release of silver ions by anchoring AgNPs on the surface or internal pores of TiO ₂ nanotubes. Furthermore, the photocatalyst can be readily separated from the system after disinfection, facilitating recycling and reuse.

The efficient electrochemical reduction of carbon dioxide to formate under mild conditions is a promising approach to mitigate the energy crisis, but requires the use of high-performance catalysts. The selectivity and activity of catalysts can be enhanced through multi-metal doping, further advancing the electrochemical reduction of CO₂ to formate. This study demonstrates a co-electrodeposition strategy for synthesizing SnBi electrocatalysts on pretreated copper foam substrates, systematically evaluating how the Sn²⁺/Bi³⁺ molar ratio in the electrodeposition solution and the applied current density affect the catalytic performance for CO₂-to-formate conversion. Optimal performance was achieved with a molar ratio of Sn²⁺ to Bi³⁺ of 1:0.5 and a deposition current density of 3 mA cm⁻², resulting in a formate Faradaic efficiency (FE_formate) of 97.80% at −1.12 V (vs. RHE) and a formate current density of 26.9 mA·cm⁻². Furthermore, the Sn₁Bi_0.50-3 mA·cm⁻² electrode demonstrated stable operation at the specified potential for 9 h, maintaining a FE_formate above 90%. Compared to previously reported metal catalysts, the SnBi catalytic electrode exhibits superior performance for the electrochemical reduction of CO₂ to HCOOH. The study highlights the significant impact of the metal ion molar ratio and deposition current density in the electrodeposition process on the characteristics and catalytic performance of the electrode.

The electrochemical CO₂ reduction reaction (CO₂RR) to formate offers a promising pathway to mitigate the energy crisis and realize carbon neutrality. Bismuth (Bi), as a metal catalyst for the CO₂RR, is considered to have great potential in producing formate, yet hindered in low current density and selectivity. Herein, we constructed an oxide-derived copper foam substrate (OD-Cu) to improve the electrocatalytic properties of Bi dendrites loaded on its surface. Bi electrodeposited on the OD-Cu (Bi/OD-Cu) grows as pinecone-like dendrites, exhibiting a high formate faradaic efficiency (FE_formate) of 97.2% and a formate partial current density of ~24 mA·cm⁻² at −0.97 V vs. RHE (reversible hydrogen electrode) in an H-cell. Notably, the Bi/OD-Cu electrode demonstrates an FE_formate of 95.8% at −0.97 V vs. RHE and a total current density close to 90 mA·cm⁻² at −1.17 V vs. RHE in a neutral flow cell. The experimental studies reveal that the remarkable CO₂RR performance of the Bi/OD-Cu results from the electron transfer from Cu to Bi, which optimizes adsorption of the CO₂^•− and boosts reaction kinetics. This study emphasizes the crucial role of substrate engineering strategies in enhancing catalytic activity and shows the possibility for a porous metal electrode in advancing the industrialization of formate production.

Effective electrochemical reduction of carbon dioxide to formate under mild conditions helps mitigate the energy crisis but requires the use of high-performance catalysts. The addition of a third metal to the binary metal catalyst may further promote the electrochemical reduction of carbon dioxide to formate. Herein, we provided a co-electrodeposition method to grow CuSnBi catalysts on pretreated copper foam and discussed the effects of both pH value and molar ratio of metal ions (Cu²⁺, Sn²⁺, and Bi³⁺) in the electrodeposition solution on the electrocatalytic performance of CO₂ to HCOO⁻. When the pH value of the electrodeposition solution was 8.5 and the molar ratio of Cu²⁺, Sn²⁺, and Bi³⁺ was 1:1:1, the electrode showed the highest FE_HCOO⁻ of 91.79% and the formate partial current density of 36.6 mA·cm⁻² at −1.12 V_RHE. Furthermore, the electrode kept stable for 20 h at −1.12 V_RHE, and FE_HCOO⁻ was always beyond 85% during the electrolysis process, which is excellent compared to the previously reported ternary metal catalytic electrodes. This work highlights the vital impact of changes (pH value and molar ratio of metal ions) in electrodeposition liquid on catalytic electrodes and their catalytic performance, and refreshing the electrolyte is essential to maintain the activity and selectivity during the electrochemical reduction of CO₂ to HCOO⁻.