Carbon‐based metal‐free catalysts for electrochemical CO2 reduction: Activity, selectivity, and stability

Zero or negative emissions of carbon dioxide(CO2)is the need of the times,as inexorable rising and alarming levels of CO2 in the atmosphere lead to global warming and severe climate change.The electrochemical CO2 reduction(eCO2R)to value‐added fuels and chemicals by using renewable electricity provides a cleaner and more sustainable route with economic benefits,in which the key is to develop clean and economical electrocatalysts.Carbon‐based catalyst materials possess desirable properties such as high offset potential for H2 evolution and chemical stability at the negative applied potential.Although it is still challenging to achieve highly efficient carbon‐based catalysts,considerable efforts have been devoted to overcoming the low selectivity,activity,and stability.Here,we summarize and discuss the recent progress in carbon‐based metal‐free catalysts including carbon nanotubes,carbon nanofibers,carbon nanoribbons,graphene,carbon nitride,and diamonds with an emphasis on their activity,product selectivity,and stability.In addition,the key challenges and future potential approaches for efficient eCO2R to low carbon‐based fuels are highlighted.For a good understanding of the whole history of the development of eCO2R,the CO2 reduction reactions,principles,and techniques including the role of electrolytes,electrochemical cell design and evaluation,product selectivity,and structural composition are also discussed.The metal/metal oxides decorated with carbon‐based electrocatalysts are also summarized.We aim to provide insights for further development of carbon‐based metal‐free electrocatalysts for CO2 reduction from the perspective of both fundamental understanding and technological applications in the future.

In-situ growth of CoNi bimetal anchored on carbon nanoparticle/nanotube hybrid for boosting rechargeable Zn-air battery

Exploring highly efficient non-precious metal based catalysts for bifunctional oxygen electrode is crucial for rechargeable metal-air batteries.In this study,with MOFs as precursors,a facile coprecipitation method is designed to realize in-situ growth of the CoNi anchored carbon nanoparticle/nanotube(CoNi/N-CNN)hybrid,which can achieve the simultaneous maximum exposure of both oxygen evolution reaction(OER)and oxygen reduction reaction(ORR)active centers.Benefiting from the unique structure,the CoNi/N-CNN catalyst exhibits excellent electrocatalytic performance for ORR(E_(onset)=1.183 V,E_(1/2)=0.819 V)and a low operating voltage of 1.718 V at 10 mA cm^(−2)(Ej=10)for OER.Delightfully,the home-made rechargeable Zn-air battery with CoNi/N-CNN delivers a high discharge power density up to 209 mW cm^(−2),and an outstanding charge–discharge cycling stability.The boosted bifunctional electrocatalytic activity can be ascribed to the strong coupling effect between Co/Ni center sites and defect-rich N-anchored carbon featured with porous and nanotube structure,which can introduce uniformly dispersed active sites,tailored electronic configuration,superb conductivity and convenient charge transfer process.The hybrid non-precious bimetal based electrocatalyst provides the possibility to develop the low-cost and high-efficient ORR/OER bifunctional electrocatalysts in rechargeable metal-air battery.

Diversity and association analysis of important agricultural trait based on miniature inverted-repeat transposable element specific marker in Brassica napus L.

Miniature inverted-repeat transposable elements(MITEs)are a group of DNA transposable element(TE)which preferentially distributed with gene associated regions.Tens of MITEs families have been revealed in Brassica napus genome,they scatter across the genome with tens of thousands copies and produce polymorphisms both intra-and inter-species.Our previous studies revealed a Tourist-like MITE,Monkey King,associated with vernalization requirement of B.napus,however there are still few studies reveal MITE association with agricultural traits in B.napus.In the present study,80 polymorphic markers were developed from 55 MITEs,and used to evaluate genetic diversity in a panel of B.napus accessions consisting of 101 natural and 25 synthetic genotypes.Five agricultural traits,oil content,glucosinolate content,erucic acid content,weight of thousand seeds(WTS)and plant height,were investigated across 3-years field experiments,in addition,two traits,hypocotyl length and root length,were evaluated at the 4-leaf stage in the laboratory.Correlations between the MITE-based markers and seven traits were analyzed,finally,10 polymorphic markers produced by 6 pairs of MITE specific primers were revealed relatively high correlation with 5 traits.Two polymorphic markers were anchored with two candidate genes,BnaA02g13530D and BnaA08g20010D,respectively,which may contribute to glucosinolate content and WTS.This research may contribute to genetic improvement through utilization of MITE-induced polymorphisms in Brassica species.

Co/Ni dual-metal embedded in heteroatom doped porous carbon core-shell bifunctional electrocatalyst for rechargeable Zn-air batteries

Rational construction of highly efficient and cheap bifunctional electrocatalysts to boost both oxygen evolution reaction(OER)and oxygen reduction reaction(ORR)is extremely essential for the wide application of rechargeable metal-air battery.In this work,we design a core-shell structural catalyst of CoNi dual-metal embedded in nitrogen doped porous carbon(NPC,CoNi@NPC),which is developed via the pyrolysis of CoNiMOFs,assisting by mesoporous SiO_(2) to effectively inhibit the aggregation of metal sites.Consequently,the asprepared CoNi@NPC manifests good ORR activity with half-wave potential up to 0.77 V.Specifically,the CoNi@NPC gives a very low OER over-potential of merely 101 mV in 6 M KOH along with high stability,outperforming the commercial Pt/C-RuO_(2).Moreover,the home-made zinc air battery with CoNi@NPC air cathode demonstrates excellent stability over long-term charging–discharging test,and delivers the maximum power density of 224 mW cm^(-2).The enhanced high performance of CoNi@NPC bifunctional catalyst for both ORR and OER can be ascribed to its unique core-shell structure and strong synergistic effect between the dual-bimetal active sites and the heteroatom doped carbon.This work opens a new avenue for the rational design of nonprecious metal bifunctional catalysts for rechargeable metal-air battery.

Overcoming the limitation of in-situ microstructural control in laser additive manufactured Ti-6Al-4V alloy to enhanced mechanical performance by integration of synchronous induction heating

Although a variety of processing routes were developed to in-situ manipulate microstructure for fabricating high-performance Ti-6Al-4 V alloy by directed energy deposition(DED),the in-situ microstructural control ability has been limited and lead to a narrowed mechanical property control range.This work proved the microstructural correlation betweenβ-grains andα-laths resulting from the unique thermal characteristics of DED for the first time and solved such a dilemma through synchronous induction heating assisted laser deposition(SILD)technology.The results confirmed that the laser energy and inductive energy have a different effect on the solidification and solid phase transformation conditions.By adjusting the laser-induction parameters,the microstructural correlation can be tuned;theβ-grains andα-laths can be controlled relatively separately,thereby significantly enhancing the ductility of as-deposited sample(elongation from 14.2%to 20.1%).Furthermore,the mechanical properties of the tuned microstructures are even comparable to that of DED Ti-6Al-4 V with post heat treatment,which indicates that the potential of SILD to be a one-step manufacturing process to fabricate high performance components without post heat treatment.Furthermore,the tensile testing results of the tuned microstructures indicate thatα-lath size is more influential on the mechanical properties than theβ-grain size due to its stronger hindering effect on the slipping of dislocations.This work promotes the understanding of the microstructural formation mechanism in DED titanium alloy and proves that the combination of synchronous induction and laser can expand the ability to control the microstructure and properties of multi-layer deposition.

Cross-Scale Synthesis of Organic High-k Semiconductors Based on Spiro-Gridized Nanopolymers

High dielectric constants in organic semiconductors have been identified as a central challenge for the improvement in not only piexoelectric,preolecric,and freeltric efcts but also photoclecric conversion eficiency in OPVs,carrier mobility in OFETS,and charge density in charge-trapping memories.Herein,we report an ultralong persistence length(≈41 nm)efet of spiro-fused organic nanopolymers on dielectric properties,together with excitonic and charge carrier behaviors.The state-of-the-art nanopolymers,namely,nanopolyspirogrids(NPSGs),are synthesized via the simple crossscale Friedel-Crafts polygridlization of AjB-type nanomonomers.The high dielectric constant(k=8.43)of NPSG is firstly achieved by locking spiro-polygridization efect that results in the enhancement of dipole polarization.When doping into a polystyrene-based dielectric layer,such a high-k feature of NPSG increases the feld-ffct carrier mobility from 0.20 to 0.90cm^(2)Vl s'in pentacene OFET devices.Meanwhile,amorphous NPSG film exhibits an ultralow energy disorder(<50 meV)for an exellent zero-field hole mobility of 3.94×10^(-1)cm^(2)V^(-1)s^(-1).surpassing most of the amorphousπconjugated polymers Onganic nanopolymers with high dielectric constants open a new way to break through the bottleneck of eficiency and multifunctionality in the blueprint of the fourth generation semiconductors.