Water extract of pomegranate ash as waste-originated biorenewable catalyst for the novel synthesis of chiral tert‑butanesulfinyl aldimines in water

Effect of Bimetallic Dimer-Embedded TiO2(101) Surface on CO2 Reduction: The First-Principles Calculation

The first-principles calculation was used to explore the effect of a bimetallic dimer-embedded anatase TiO₂(101) surface on CO₂ reduction behaviors. For the dimer-embedded anatase TiO₂(101) surface, Zn-Cu, Zn-Pt, and Zn-Pd dimer interstitials could stably stay on the TiO₂(101) surface with a binding energy of about −2.36 eV, as well as the electronic states’ results. Meanwhile, the results of adsorption energy, structure parameters, and electronic states indicated that CO₂ was first physically and then chemically adsorbed much more stably on these three kinds of dimer-embedded TiO₂(101) substrate with a small barrier energy of 0.03 eV, 0.23 eV, and 0.12 eV. Regarding the reduction process, the highest-energy barriers of the CO₂ molecule on the Zn-Cu dimer-embedded TiO₂(101) substrate was 0.31 eV, which largely benefited the CO₂-reduction reaction (CO₂RR) activity and was much lower than that of the other two kinds of Zn-Pt and Cu-Pt dimer-TiO₂ systems. Simultaneously, the products CO* and *O* of CO₂ reduction were firmly adsorbed on the dimer-embedded TiO₂(101) surface. Our results indicated that a non-noble Zn-Cu dimer might be a more suitable and economical choice, which might theoretically promote the designation of high CO₂RR performance on TiO₂ catalysts.

Nanosheets with High-Performance Electrochemical Oxygen Reduction Reaction Revived from Green Walnut Peel

The synthesis of metal-free carbon-based electrocatalysts for oxygen reduction reactions (ORR) to replace conventional Pt-based catalysts has become a hot spot in current research. This work proposes an activation-assisted carbonization strategy, to manufacture N-doped ultra-thin carbon nanosheets (GWS180M800) with high catalytic activity, namely, melamine is used as an accelerator/nitrogen source, and walnut green peels biological waste as a carbon source. The melamine acts as a nitrogen donor in the hydrothermal process, effectively enhancing the nitrogen doping rate. The content of pyridine nitrogen groups accounts for up to 48.5% of the total nitrogen content. Electrochemical tests show that the GWS180M800 has excellent ORR electrocatalytic activity and stability, and makes a quasi-four-electron ORR pathway clear in the alkaline electrolyte. The initial potential and half slope potential are as high as 1.01 and 0.82 V vs. RHE, respectively. The GWS180M800 catalyst has a better ability to avoid methanol cross poisoning than Pt/C has. Compared with 20 wt% Pt/C, GWS180M800 has improved methanol tolerance and stability. It is a metal-free biochar ORR catalyst with great development potential and application prospects. This result provides a new space for the preparation of valuable porous nano-carbon materials based on carbonaceous solid waste and provides new ideas for catalyzing a wide range of electrochemical reactions in the future.