Despite high-energy density and low cost of the lithium-sulfur (Li-S) batteries, their commercial success is greatly impeded by their severe capacity decay during long-term cycling caused by polysulfide shuttling. Herein, a new phase engineering strategy is demonstrated for making MXene/1T-2H MoS 2 -C nanohybrids for boosting the performance of Li-S batteries in terms of capacity, rate ability, and stability. It is found that the plentiful positively charged S-vacancy defects created on MXene/1T-2H MoS 2 -C, proved by high-resolution transmission electron microscopy and electron paramagnetic resonance, can serve as strong adsorption and activation sites for polar polysulfide intermediates, accelerate redox reactions, and prevent the dissolution of polysulfides. As a consequence, the novel MXene/1T-2H MoS 2 -C-S cathode delivers a high initial capacity of 1194.7 mAh g −1 at 0.1 C, a high level of capacity retention of 799.3 mAh g −1 after 300 cycles at 0.5 C, and reliable operation in soft-package batteries. The present MXene/1T-2H MoS 2 -C becomes among the best cathode materials for Li-S batteries.

1. Accurate assessments of fish species diversity and community composition are essential for understanding fish ecology and conservation management. Environmental DNA (eDNA) metabarcoding has become an integrated method for monitoring fish species. The accuracy and efficacy of eDNA metabarcoding rely heavily on the choice of primers used for PCR amplification. A wide selection of metabarcoding primers for fish has been developed; however, there exists no comprehensive and comparative evaluation of their amplification or taxonomic classification of a rich diversity of fish species, which hinders informed decisions regarding their suitability for different study systems. 2. Here we reviewed the literature and compiled a list of 22 primer sets for eDNAbased metabarcoding analysis of teleost fish, the performance of which was compared using in silico PCR, followed by in vitro metabarcoding analysis using eDNA from waterbodies in Beijing, which harbour a high number of freshwater fish species. 3. We found that the primers showed considerable differences in the amplified taxonomic ranges and proportions, fish taxa richness, species discrimination power and fish community compositions, both in silico and in vitro. The number of fish taxa detected from eDNA by the primer sets varied from 0 to 66. Primers targeting the 12S rRNA gene generally detected greater fish diversity than those targeting the 16S rRNA or COI genes, while primers targeting the cytochrome b gene amplified the fewest fish taxa in vitro. 4. Regarding target genes, 12S primers generally outperformed other primers in terms of amplified fish diversity. The results of in silico PCR and in vitro tests were not always in agreement, suggesting that primer choice for biodiversity surveys should not be based solely on in silico evaluation. The use of different primers can qualitatively and quantitatively affect the detected biodiversity and these effects should be considered in experimental design and data interpretation. These results will assist with primer selection for eDNA-based fish surveys, and consequently support conservation of freshwater biodiversity.

Excavating and developing highly efficient and cost‐effective nonnoble metal single‐atom catalysts for electrocatalytic reactions is of paramount significance but still in its infancy. Herein, reported is a general NaCl template‐assisted strategy for rationally designing and preparing a series of isolated transition metal single atoms (Fe/Co/Ni) anchored on honeycomb‐like nitrogen‐doped carbon matrix (M1‐HNC‐T1‐T2, M = Fe/Co/Ni, T1 = 500 °C, T2 = 850 °C). The resulting M1‐HNC‐500‐850 with M‐N4 active sites exhibits superior capability for oxygen reduction reaction (ORR) with the half‐wave potential order of Fe1‐HNC‐500‐850 > Co1‐HNC‐500‐850 > Ni1‐HNC‐500‐850, in which Fe1‐HNC‐500‐850 shows better performance than commercial Pt/C. Density functional theory calculations reveal a choice strategy that the strong p–d‐coupled spatial charge separation results the Fe‐N4 effectively merges active electrons for elevating d‐band activity in a van‐Hove singularity like character. This essentially generalizes an optimal electronic exchange‐and‐transfer (ExT) capability for boosting sluggish alkaline ORR activity. This work not only presents a universal strategy for preparing single‐atom electrocatalyst to accelerate the kinetics of cathodic ORR but also provides an insight into the relationship between the electronic structure and the electrocatalytical activity.

Designing well‐defined nanointerfaces is of prime importance to enhance the activity of nanoelectrocatalysts for different catalytic reactions. However, studies on non‐noble‐metal‐interface electrocatalysts with extremely high activity and superior stability at high current density still remains a great challenge. Herein, a class of Co3O4/Fe0.33Co0.66P interface nanowires is rationally designed for boosting oxygen evolution reaction (OER) catalysis at high current density by partial chemical etching of Co(CO3)0.5(OH)·0.11H2O (Co‐CHH) nanowires with Fe(CN)63−, followed by low‐temperature phosphorization treatment. The resulting Co3O4/Fe0.33Co0.66P interface nanowires exhibit very high OER catalytic performance with an overpotential of only 215 mV at a current density of 50 mA cm−2 and a Tafel slope of 59.8 mV dec−1 in 1.0 m KOH. In particular, Co3O4/Fe0.33Co0.66P exhibits an obvious advantage in enhancing oxygen evolution at high current density by showing an overpotential of merely 291 mV at 800 mA cm−2, much lower than that of RuO2 (446 mV). Co3O4/Fe0.33Co0.66P is remarkably stable for the OER with negligible current loss under overpotentials of 200 and 240 mV for 150 h. Theoretical calculations reveal that Co3O4/Fe0.33Co0.66P is more favorable for the OER since the electrochemical catalytic oxygen evolution barrier is optimally lowered by the active Co‐ and O‐sites from the Co3O4/Fe0.33Co0.66P interface.