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Graphdiyne (GDY) has been considered as an appealing anode candidate for K-ion storage since its triangular pore channel, alkyne-rich structure, and large interlayer spacing would endow it with abundant active sites and ideal diffusion paths for K-ions. Nevertheless, the low surface area and disordered structure of bulk GDY typically lead to unsatisfied K storage performance. Herein, we have designed a GDY/graphene/GDY (GDY/Gr/GDY) sandwiched architecture affording a high surface area and fine quality throughout a van der Waals epitaxy strategy. As tested in a half-cell configuration, the GDY/Gr/GDY electrode exhibits better capacity output, rate capability, and cyclic stability as compared to the bare GDY counterpart. In situelectrochemical impedance spectroscopy/Raman spectroscopy/transmission electron microscopy are further applied to probe the K-ion storage feature and disclose the favorable reversibility of GDY/Gr/GDY electrode during repeated potassiation/depotassiation. A full-cell device comprising a GDY/Gr/GDY anode and a potassium Prussian blue cathode enables a high cycling stability, demonstrative of the promising potential of the GDY/Gr/GDY anode for K-ion batteries.

A N-doped graphene/ReSe2/MXene heterostructure is enabled by all-CVD route, readily demonstrating high-rate K-ion storage performance as hybrid anode candidate.

The potassium–selenium (K–Se) battery has been considered an appealing candidate for next-generation energy storage systems owing to the high energy and low cost. Nonetheless, its development is plagued by the tremendous volume expansion and sluggish reaction kinetics of the Se cathode. Moreover, implementing favorable areal capacity and longevous cycling of a high-loading K–Se battery remains a daunting challenge facing commercial applications. Herein, we devise a Se and CoNiSe2coembedded nanoreactor (Se/CoNiSe2–NR) affording low carbon content as an advanced cathode for K–Se batteries. We systematically uncover the enhanced K2Se2/K2Se adsorption and promoted K+diffusion behavior with the incorporation of Co throughout theoretical simulation and electrokinetic analysis. As a result, Se/CoNiSe2–NR harvests high cycling stability with a capacity decay rate of 0.038% per cycle over 950 cycles at 1.0 C. More encouragingly, equipped with a 3D-printed Se/CoNiSe2–NR electrode with tunable Se loadings, K–Se full batteries enable steady cycling at an elevated Se loading of 3.8 mg cm–2. Our endeavor ameliorates the capacity and lifetime performance of the emerging K–Se device, thereby offering a meaningful tactic in pursuing its practical application.

Antibiotic residues in the environment and in foods pose a serious threat to ecosystems and human health. Developing sensitive and on-site detection methods is therefore in high demand. In this work, a portable paper-based colorimetric sensor with a smartphone platform with an ultrahigh sensitivity has been designed for on-site and quantitative analysis of antibiotic residues based on aptamer-regulated nanozyme activity. The developed excellent peroxidase-like nanozymes, carbon-protected NiCo bimetal oxides with a unique hollow nanocage structure (NiCo@C HCs), could effectively catalyze the oxidation of chromogenic substrates by H2O2. Once bound to a specific aptamer, the enzyme-mimicking activity of NiCo@C HCs is obviously inhibited as a result of the masking of active sites but could be restored via the target-aptamer recognition. Herein, the aptamer-modified NiCo@C HCs are embedded on paper pieces to construct paper-based biochips for visual detection. Meanwhile, a smartphone platform is integrated for the signal readout. Using enrofloxacin (ENR) as an analyte model, the proposed paper-based analysis platform shows a reliable and sensitive detection of ENR with an ultralow detection limit of 0.029 ng/mL. The platform also works well in various real samples. This analysis method is facile in design, showing a great application potential for on-site and mass screening of antibiotic residues in the environment and in foods.

Decentralized H2O2production from a 2e–oxygen reduction reaction (ORR) pathway is appealing, wherein the rational design of electrocatalysts is the cornerstone rendering favorable catalytic activity/selectivity. Nevertheless, the real active moiety is elusive and the catalyst evolution during the reaction remains unexplored to date. Herein, we decipher in situevolved surface chemistry of a Ni-based precatalyst (Ni SAC/Ni-NiO/NC-500) during the 2e–ORR process that results in a reconstructed catalyst (Ni SAC/Ni-NiO/NC-500-R). The phase transformation of the electrocatalyst is monitored by operandoRaman spectroscopy and ex situX-ray analysis. With the optimized catalyst in hand, a 2e–ORR potential of 0.78 V (at 1.0 mA cm–2) and a high selectivity of 95% in an alkaline electrolyte are harvested. More encouragingly, high-flux H2O2is produced viaphotomediated electrosynthesis, enabling on-site degradation of organic pollutants with an impressive degradation rate approaching 100%.