Single site catalyst with enzyme-mimic micro-environment for electroreduction of CO_(2)

Single site catalysts provide a unique platform for mimicking natural enzyme due to their tunable interaction between metal center and coordinated ligand.However,most works have focused on preparing structural and functional models of nature enzyme,with less reports also taking the local chemical environment,i.e.,functional/catalytic residues around the active site which is an essential feature of enzymes,into consideration.Herein,we report a Co-centered porphyrinic polymer containing the enzyme-mimic micro-environment,where the linker triazole over CoN4 site enables formation of hydrogen bond with the*COOH intermediate,thus promoting the electrocatalytic reduction of CO_(2).As-prepared catalyst achieves the CO_(2)-to-CO conversion of 5,788 h^(−1) turnover frequency value and near unit(~96%)faradaic efficiency at−0.61 V versus reversible hydrogen electrode.This strategy will bring new dimension of designing highly active single-site catalysts.

Surface modification of nanozymes

Nanoparticles and proteins are similar in a number of aspects, and using nanoparticles to mimic the catalytic function of enzymes is an interesting yet challenging task. Impressive developments have been made over the past two decades on this front. The term nanozyme was coined to refer to nanoparticle- based enzyme mimics. To date, many different types of nanozymes have been reported to catalyze a broad range of reactions for chemical, analytical, and biomedical applications. Since chemical reactions happen mainly on the surface of nanozymes, an interesting aspect for investigation is surface modification. In this review, we summarize three types of nanozyme materials catalyzing various reactions with a focus on their surface chemistry. For metal oxides, cerium oxide and iron oxide are discussed as they are the most extensively studied. Then, gold nanoparticles and graphene oxide are reviewed to represent metallic and carbon nanomaterials, respectively. Types of modifications include ions, small molecules, and polymers mainly by physisorption, while in a few cases, covalent modifications were also employed. The functional aspect of such modification is to improve catalytic activity, substrate specificity, and stability. Future perspectives of this field are speculated at the end of this review.

Nanozyme Based Detection of Heavy Metal Ions and its Challenges: A Minireview

Naznozymes have become an important alternative to natural enzymes for many sensing applications,due to their relatively high stability,easy synthesis,and cost-effectiveness.Nanozyme-based assays,especially paper-based assays are portable,and therefore,are convenient for use in field operations,especially in remote parts of the world.Decreasing water levels,depletion of water resources,and large scale mining create the need for rapid detection of heavy metal ions in various water samples.In comparison with traditional methods of heavy metal ion detection,nanozyme-based systems enable rapid and cheap screening on the spot with a very simple instrument such as a UV-Vis absorption spectrophotometer.The sensing mechanism of a nanozyme-based sensor is highly dependent on its surface properties.They often encounter selectivity issues,unlike natural enzyme-based assays.Therefore,different types of target recognition and inhibition/enhancement mechanisms have been reported to achieve high selectivity.In this short review,we mainly focus our discussion on various interaction of the heavy metal ions with the nanozyme,and their responses towards the catalytic activity in the sensing of target metal ions.