An updated comprehensive review to help researchers understand nanozymes better and in turn to advance the field.

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efficiency (CE) and cycling performance. [2] In addition, the lithium polysulfides dissolution and Li dendrite growth also require a large amount excess electrolyte to achieve high performance, thus reducing the energy density. Extensive efforts have been devoted to suppress "shuttle" of lithium polysulfide. Among them, encapsulating sulfur cathode into porous host materials including porous carbon, [3] metal oxide/chalcogenide, [4] and conductive polymers [5] are the most effective method for suppressing "shuttle" effect. On the Li anode side, nanostructure design [6] or surface modification [7] has been also developed to suppress the dendritic Li growth.Different from separately nanostructured design of the electrodes, rational design and optimization of electrolytes are more effective, [8] which simultaneously suppress both lithium polysulfide shuttle and Li dendrite. [9] Recently, highly concentrated electrolyte (HCE) systems with unique solvation structure and functionality have been successfully developed for high performance Li-S batteries. For example, Suo et al. showed a new class of ultrahigh salt concentration electrolyte, which can effectively suppress the lithium dendrite growth and inhibit the polysulfide shuttle phenomenon in Li-S batteries. [2c] Qian et al. reported that the high-concentration electrolytes enabled the high-rate cycling of lithium metal with a high CE up to 99.1% without dendrite growth. [2a] These significant performance improvements were contributed to the strong restraining property for the solvents from the high-concentrated salts in electrolyte that efficiently control the reaction dynamics and Li 2 S n solubility synchronously. These exciting breakthroughs demonstrated that such unique HCE systems can offer new possibilities to address the shuttle effect and dendritic Li growth efficiently and simultaneously.Nevertheless, the usage of a large amount of expensive lithium salt in the HCE systems also lead to several disadvantages, including high cost, poor wettability, high viscosity, and low ionic conductivity. [10] To address these issues without scarifying the unique characteristics of HCE, a new kind of localized high-concentration electrolyte (LHCE) was proposed by using a rational cosolvent dilution in HCE system. The choice of the cosolvent in LHCE is critical for the performance of Li-S batteries. In Li-S battery electrolytes, ether-based solvents with high donor number were usually employed, which can effectively dissociate the Li + from anion and dissolve Li salts. However, the strong donating ability of such solvents can also facilitate the dissolution of long-chain polysulfide and amplify Rechargeable Li-S batteries are regarded as one of the most promising next-generation energy-storage systems. However, the inevitable formation of Li dendrites and the shuttle effect of lithium polysulfides significantly weakens electrochemical performance, preventing its practical application. Herein, a new class of localized high-concentration electrolyte (LHCE) enabled ...

A peroxidase catalyzes the oxidation of a substrate with a peroxide. The search for peroxidase-like and other enzyme-like nanomaterials (called nanozymes) mainly relies on trial-and-error strategies, due to the lack of predictive descriptors. To fill this gap, here we investigate the occupancy of eg orbitals as a possible descriptor for the peroxidase-like activity of transition metal oxide (including perovskite oxide) nanozymes. Both experimental measurements and density functional theory calculations reveal a volcano relationship between the eg occupancy and nanozymes’ activity, with the highest peroxidase-like activities corresponding to eg occupancies of ~1.2. LaNiO3-δ, optimized based on the eg occupancy, exhibits an activity one to two orders of magnitude higher than that of other representative peroxidase-like nanozymes. This study shows that the eg occupancy is a predictive descriptor to guide the design of peroxidase-like nanozymes; in addition, it provides detailed insight into the catalytic mechanism of peroxidase-like nanozymes.

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The detection of phosphates and their enzymatic hydrolysis is of great importance because of their essential roles in various biological processes and numerous diseases. Compared with individual sensors for detecting one given phosphate at a time, sensor arrays are able to discriminate multiple phosphates simultaneously. Although nanomaterial-based sensor arrays have shown great promise for the discrimination of phosphates, very few of them have been explored for probing phosphates involved enzymatic hydrolysis. To fill this gap, herein we fabricated two-dimensional-metal-organic-framework (2D-MOF)-nanozyme-based sensor arrays by modulating their peroxidase-mimicking activity with various phosphates, including AMP, ADP, ATP, pyrophosphate (PPi), and phosphate (Pi). The sensor arrays were used to successfully discriminate the five phosphates not only in aqueous solutions but also in biological samples. The practical application of the sensor arrays was then validated with blind samples, where 30 unknown samples containing phosphates were accurately identified. Moreover, the sensor arrays were successfully applied to probing hydrolytic processes involving ATP and PPi that are catalyzed by apyrase and PPase, respectively. This work demonstrates a nanozyme-based sensor array as a convenient and reliable analytical platform for probing phosphates and their related enzymatic processes, which could be applied to other analytes and enzymatic reactions.

Nanozymes have emerged as promising alternatives to overcome the high cost and low stability of natural enzymes. Nanozymes with peroxidase-like activities have been studied to construct versatile biosensors by using specific biorecognition ligands (such as enzymes, antibodies, and aptamers) or molecularly imprinted polymers (MIPs). However, the use of bioligands compromises the high stability and low cost promise of nanozymes, while the MIPs may not be applicable to multiplex detection. To address these limitations, here we constructed the nanozyme sensor arrays based on peroxidase-like Pt, Ru, and Ir nanozymes. The cross-reactive nanozyme sensor arrays were successfully used for the detection of biothiols and proteins as well as the discrimination of cancer cells because of the differential nonspecific interactions between the components of the sensor arrays and the analytes. The usefulness of the nanozyme sensor arrays was further validated by the detection of blind unknown samples, where 28 of 30 biothiols and 42 of 45 proteins were correctly identified. Moreover, the practical application of the nanozyme sensor arrays was demonstrated by the successful discrimination of biothiols in serum and proteins in human urine.