Main Group SnN4O Single Sites with Optimized Charge Distribution for Boosting the Oxygen Reduction Reaction.

Transition metal single-atom catalysts (SACs) have been regarded as possible alternatives to platinum-based materials due to their satisfactory performance of the oxygen reduction reaction (ORR). By contrast, main-group metal elements are rarely studied due to their unfavorable surface and electronic states. Herein, a main-group Sn-based SAC with penta-coordinated and asymmetric first-shell ligands is reported as an efficient and robust ORR catalyst. The introduction of the vertical oxygen atom breaks the symmetric charge balance, modulating the binding strength to oxygen intermediates and decreasing the energy barrier for the ORR process. As expected, the prepared Sn SAC exhibits outstanding ORR activity with a high half-wave potential of 0.912 V (vs RHE) and an excellent mass activity of 13.1 A mgSn-1 at 0.850 V (vs RHE), which surpasses that of commercial Pt/C and most reported transition-metal-based SACs. Additionally, the reported Sn SAC shows excellent ORR stability due to the strong interaction between Sn sites and the carbon support with oxygen atom as the bridge. The excellent ORR performance of Sn SAC was also proven by both liquid- and solid-state zinc-air battery (ZAB) measurements, indicating its great potential in practical applications.

Recent Developments of Dual Single-Atom Catalysts for Nitrogen Reduction Reaction.

Ammonia is vital for fertilizer production, hydrogen storage, and alternative fuels. The conventional Haber-Bosch process for ammonia production is energy-intensive and environmentally harmful. Designing environmentally friendly and low-energy consumption strategies for electrocatalytic N2 reduction reaction (ENRR) in mild conditions is meaningful. Single-atom catalysts (SACs) have been studied extensively for NRR due to their high atomic utilization and unique electronic structure but are limited by their poor faradic efficiency and low ammonia formation yield. Dual single-atom catalysts (DSACs) have recently emerged as a promising solution for the effective activation of molecular N2 , providing diverse active sites and synergistic interactions between adjacent atoms. In this review, we summarize the latest advances in metal DSACs for electrochemical ENRR based on both theoretical calculations and experimental studies, including aspects such as their variety, coordination, support, N2 adsorption and activity mechanisms, the characterization of NRR and electrochemical cell Configuration. We also address challenges and prospects in this rapidly evolving field, providing a comprehensive overview of DSACs for ENRR.

Responses of tree seedlings to understory filtering by the recalcitrant fern layer in a subtropical forest.

The recalcitrant understory fern layer is an important ecological filter for seedling regeneration, yet how the fern layer influences seedling regeneration dynamics remains unclear. Here we transplanted 576 seedlings of four dominant tree species, Castanopsis fargesii, Lithocarpus glaber, Schima superba and Hovenia acerba, to the treatments of Diplopterygium glaucum retention and removal under an evergreen broad-leaved forest in eastern China. We monitored the survival, growth and biomass data of these seedlings for 28 months, and then used generalized linear mixed models to evaluate the treatment effects on seedling survival, growth, biomass and root-shoot ratio. Our results showed that fern retention significantly inhibited the seedling establishment of all four species. During the seedling development stage, the seedling relative growth rate of L. glaber decreased under fern retention, which was not the case for the other three species. Root-shoot ratio of C. fargesii and L. glaber increased significantly under fern retention. Our findings provide new evidence of the filtering effect of a recalcitrant fern understory. Notably, we observed that the response of tree seedlings to the recalcitrant fern understory was more sensitive in the establishment stage. Finally, our work highlights that the filtering effect of the recalcitrant fern understory changes depending on the regeneration stages, and that shade-tolerant species, C. fargesii and L. glaber were even more affected by fern disturbed habitats, suggesting that effective management should attempt to curb forest fern outbreaks, thus unblocking forest recruitment.

Restructuring highly electron-deficient metal-metal oxides for boosting stability in acidic oxygen evolution reaction.

The poor catalyst stability in acidic oxidation evolution reaction (OER) has been a long-time issue. Herein, we introduce electron-deficient metal on semiconducting metal oxides-consisting of Ir (Rh, Au, Ru)-MoO3 embedded by graphitic carbon layers (IMO) using an electrospinning method. We systematically investigate IMO's structure, electron transfer behaviors, and OER catalytic performance by combining experimental and theoretical studies. Remarkably, IMO with an electron-deficient metal surface (Irx+; x > 4) exhibit a low overpotential of only ~156 mV at 10 mA cm-2 and excellent durability in acidic media due to the high oxidation state of metal on MoO3. Furthermore, the proton dissociation pathway is suggested via surface oxygen serving as proton acceptors. This study suggests high stability with high catalytic performance in these materials by creating electron-deficient surfaces and provides a general, unique strategy for guiding the design of other metal-semiconductor nanocatalysts.

Z-Scheme Au@Void@g-C3N4/SnS Yolk-Shell Heterostructures for Superior Photocatalytic CO2 Reduction under Visible Light.

Au@g-C3N4/SnS yolk-shell Z-scheme photocatalysts are fabricated by a simple template-assisted strategy. The l-cysteine can offer the amine groups and meanwhile anchor on the surface of g-C3N4 during solvothermal reaction and thus contributes greatly to the enhanced carbon dioxide adsorption capability. This Z-scheme photocatalytic reduction mechanism of Au@g-C3N4/SnS performs valuable functions in the reaction, leading to CH4 generation much earlier and higher concentration than that of Au@g-C3N4. Meanwhile, the unique yolk-shell structure can make the light bounce back and forth in the cavity and thus enhances the availability ratio of light. The application of small amount of noble metal cocatalysts and the large Brunauer-Emmett-Teller surface areas are also benefited for the enhanced photocatalytic activities. Hence, this novel material exhibits a distinguished reduction performance for CO2 reduction under visible light. The highest yields of CH4 (3.8 µmol g-1), CH3OH (5.3 µmol g-1), and CO (17.1 µmol g-1) can be obtained for the sample of Au@g-C3N4/SnS (SnS 41.5%), which is higher than other latest reported g-C3N4-based photocatalysts for CO2 photoreduction including coupled with semiconductors and noble metal cocatalysts. This strategy might represent a novel way for the effective transition of CO2 to clean fuels and can also be enormous feasible utilization in the photocatalytic field.

Controlled synthesis of hollow octahedral ZnCo2O4 nanocages assembled from ultrathin 2D nanosheets for enhanced lithium storage.

Hollow octahedral ZnCo2O4 nanocages assembled from ultrathin 2D nanosheets are prepared through facile fast simultaneous coordinating etching and thermal processes. Electrochemical results show that the hollow octahedral ZnCo2O4 nanocage is an outstanding anode material for LIBs with a high reversible discharge capacity of 1025 mA h g-1 at 500 mA g-1 after 200 cycles, and an outstanding rate capability of 525 mA h g-1 at 4 A g-1. Moreover, this simple, low cost and fast process could be useful for the construction of many other hollow advanced materials for supercapacitors, sensors and other novel energy and environmental applications.