The complex structure of nanomaterial causes great difficulty in identifying active sites of nanozymes and getting to the bottom of the catalytic mechanism. In this report, single-atom Bi-anchored Au (BiSA@Au) hydrogels were synthesized through a one-step reduction strategy, which enables the precise regulation of the nanozyme activity and specificity at the atomic scale and the in-depth understanding of their catalytic nature. Due to the single-atom Bi doping, the BiSA@Au hydrogels showed previously unachieved peroxidase (POD)-like activity, while the doped single Bi atoms had negligible effects on the enhancements of the other closely related redox enzyme-like activities. Density functional theory verified that the introduction of single Bi atoms not only enhances the adsorption of H 2 O 2 but also decreases the potential barriers for *OOH generation, leading to the boosted POD-like activity. Taking advantage of the unique porous nanowire networks of BiSA@Au hydrogels, a nanozyme/natural enzyme hybrid cascade reaction system was fabricated to achieve the sensitive colorimetric biosensor for glucose. This work paved a new route to rationally design functional nanozymes at the atomic scale, achieving the significant enhancement of POD-like activity with exceptional specificity.
Si Haibin,Du Dexin,Jiao Chengcheng,Sun Yan,Li Lu,Tang Bo
In enzymatic catalysis, the redox site and Lewis acid are the two main roles played by metal to assist amino acids. However, the reported enzyme mimics only focus on the redox-active metal as redox site, while the redox-inert metal as Lewis acid has, to the best of our knowledge, not been studied, presenting a bottleneck of enzyme mimics construction. Based on this, a series of highly efficient M x V 2 O 5 ·nH 2 O peroxidase mimics with vanadium as redox site and alkaline-earth metal ion (M 2+ ) as Lewis acid are reported. Experimental results and theoretical calculations indicate the peroxidase-mimicking activity of M x V 2 O 5 ·nH 2 O show a periodic change with the Lewis acidity (ion potential) of M 2+ , revealing the mechanism of redox-inert M 2+ regulating electron transfer of V-O through non-covalent polarization and thus promoting H 2 O 2 adsorbate dissociation. The biomimetic synergetic effect of redox site and Lewis acid is expected to provide an inspiration for design of enzyme mimics.
Fengyue Zhao,Juan Xiao,Shipeng Geng,Yi Wang,Panagiotis Tsiakaras,Shuqin Song
Fe 3+ /Fe 2+ interconversion is one of the key factors for heterogeneous electro-Fenton degradation of organic pollutants. In this study, MIL-101Fe-derived carbon wrapping Fe 7 S 8 nanocomposite (Fe 7 S 8 /C-1-600) exhibits outstanding rhodamine B (RhB) degradation ability with extremely low iron leaching and high recyclable degradability within 60 min in a wide pH range. Moreover, Fe 7 S 8 /C-1-600 presents a much higher activity for RhB degradation than Fe 3 O 4 counterpart without sulfidation, which could be mainly attributed to the accelerated Fe 3+ /Fe 2+ cycling by iron with both multiple valences (Fe 0 , Fe 2+ , and Fe 3+ ) and sulfur species (S 2− and S 2 2− ) of the catalyst. The enhancement of H 2 O 2 adsorption and activation into OH on Fe 7 S 8 surface is confirmed by density functional theory calculations with respect to that on Fe 3 O 4 . Interestingly, SO 4 · − can be generated by reacting S 2 2− with dissolved O 2 and subsequently converted into ·OH, which further facilitates RhB degradation. These findings may shed a new insight into the potential application of metal sulfides for wastewater treatment.
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