Introducing hydroxyl groups to tailor the d-band center of Ir atom through side anchoring for boosted ORR and HER

Tuning the coordination atoms of central metal is an effective means to improve the electrocatalytic activity of atomic catalysts.Herein,iridium(Ir) is proposed to be asymmetrically anchored by sp-N and pyridinic N of hydrogen-substituted graphdiyne(HsGDY),and coordinated with OH as an Ir atomic catalyst(Ir_(1)-N-HsGDY).The electron structures,especially the d-band center of Ir atom,are optimized by these specific coordination atoms.Thus,the as-synthesized Ir_(1)-N-HsGDY exhibits excellent electrocatalytic performances for oxygen reduction and hydrogen evolution reactions in both acidic and alkaline media.Benefiting from the unique structure of HsGDY,IrN_(2)(OH)_(3) has been developed and demonstrated to act as the active site in these electrochemical reactions.All those indicate the fresh role of the sp-N in graphdiyne in producing a new anchor way and contributing to promote the electrocatalytic activity,showing a new strategy to design novel electrochemical catalysts.

Electrochemical synthesis of FeN_(x) doped carbon quantum dots for sensitive detection of Cu^(2+) ion

A novel strategy was developed to fabricate FeNx-doped carbon quantum dots(Fe-N-CQDs)to detect Cu^(2+) ions selectively as a fluorescence probe.The Fe-N-CQDs were synthesized by an efficient electrolysis of a carbon cloth electrode,which was coated with monoatomic ironanchored nitrogen-doped carbon(Fe-N-C).The obtained Fe-N-CQDs emitted blue fluorescence and possessed a quantum yield(QY)of 7.5%.An extremely wide linear relationship between the Cu^(2+) concentration and the fluorescence intensity was obtained in the range from 100 nmol L^(-1) to 1000 nmol L^(-1)(R^(2)=0.997),and the detection limit was calculated as 59 nmol L^(-1).Moreover,the Fe-N-CQDs demonstrated wide range pH compatibility between 2 and 13 due to the coordination between pyridine nitrogen and Fe^(3+),which dramatically reduced the affection of the protonation and deprotonation process between H^(+) and Fe-N-CQDs.It is notable that the Fe-N-CQDs exhibited a rapid response in Cu^(2+) detection,where stable quenching can be completed in 7 s.The mechanism of excellent selective detection of Cu^(2+) was revealed by energy level simulation that the LUMO level of Fe-N-CQDs(-4.37 eV)was close to the redox potential of Cu^(2+),thus facilitating the electron transport from Fe-N-CQDs to Cu^(2+).

The preparation of whole sp-C composed alkyne rich carbon materials

For the high content of sp-hybridized carbon atoms,carbyne based materials can express superior conductivity and ultra-high theoretical capacity,which are key factors of high-performance anode.However,the poor stability of synthetic intermediates and unwanted side reactions lead to huge challenge to synthesis carbyne alternating carbon–carbon triple and single bonds.Here,we rationally designed a smart“Greedy Snake”strategy to synthesize the alkyne rich carbon materials named Si capped alkyne rich carbon(Si-Alkyne-C)which comprised of sp-hybridized carbon atoms.The as-prepared Si-Alkyne-C generated on the copper surface through a carbon–carbon coupling,in which Si can effectively protect the intermediates generated by the reaction.The C–Si bond can constantly generate copper-alkyne intermediates to couple with other terminal alkynes to continuously elongate like"Greedy Snake",forming a long alkyne chain structure.The as-prepared Si-Alkyne-C can be applied as anode electrodes,exhibited very high reversible capacity of up to 2776 mAh/g at a current density of 50 mA/g and an average capacity around 1202 mAh/g at a high current density of 5000 mA/g for 5000 cycles,which are the best results among the reported carbon materials and better than many other anode materials.These results not only provide a facile strategy to prepare carbyne based materials,but also open a broad avenue for the preparation of high-capacity anode materials.

Magnetic coupling engineered porous dielectric carbon within ultralow filler loading toward tunable and high-performance microwave absorption

Developing microwave absorption(MA)materials with satisfied comprehensive performance is a great challenge for tackling severe electromagnetic pollution.In particular,the magnetic component/carbon hybrids absorbers always suffer from high filler loading.Herein,we propose a feasible strategy to construct hierarchical porous carbon with tightly embedded Ni nanoparticles(Ni@NPC).These highly dispersed Ni nanoparticles produce strong magnetic coupling networks to enhance magnetic loss abilities.Moreover,the interconnected hierarchical dielectric carbon network affords favorable dipolar/interfacial polarization,conduction loss,multiple reflection and scattering.Impressively,with an ultralow filler loading of 5 wt.%,the resultant Ni@NPC/paraffin composite achieves an excellent MA performance with a minimum reflection loss of as high as-72.4 dB and a broad absorption bandwidth of 5.0 GHz.This capability outperforms most current magnetic-dielectric hybrids counterparts.Furthermore,the MA capacity can be easily tuned with adjustments in thickness,content and type of magnetic material.Thus,this work opens up new avenues for the development of high-performance and lightweight MA materials.