In situ trapped high-density single metal atoms within graphene： Iron-containing hybrids as representatives for efficient oxygen reduction

Atomically dispersed catalysts have attracted attention in energy conversion applications because their efficiency and chemoselectivity for special catalysis are superior to those of traditional catalysts. However, they have limitations owing to the extremely low metal-loading content on supports, difficulty in the precise control of the metal location and amount as well as low stability at high temperatures. We prepared a highly doped single metal atom hybrid via a single-step thermal pyrolysis of glucose, dicyandiamide, and inorganic metal salts. High-angle annular dark field-scanning transmission electron microscopy （HAADF-STEM） and X-ray absorption fine structure spectroscopy （XAFS） revealed that nitrogen atoms doped into the graphene matrix were pivotal for metal atom stabilization by generating a metal-Nx coordination structure. Due to the strong anchoring effect of the graphene matrix, the metal loading content was over 4 wt.% in the isolated atomic hybrid （the Pt content was as high as 9.26 wt.% in the Pt-doped hybrid）. Furthermore, the single iron-doped hybrid （Fe@N-doped graphene） showed a remarkable electrocatalytic performance for the oxygen reduction reaction. The peak power density was - 199 mW·cm-2 at a current density of 310 mA·cm-2 and superior to that of a commercial Pt/C catalyst when it was used as a cathode catalyst in assembled zinc-air batteries. This work offered a feasible approach to design and fabricate highly doped single metal atoms （SMAs） catalysts for potential energy applications.

Nanoscale engineering of conducting polymers for emerging applications in soft electronics

Soft electronics featuring exceptional mechanical compliance and excellent electrical performance hold great promise for applications in soft robotics,artificial intelligence,bio-integrated electronics,and wearable electronics.Intrinsically stretchable and conductive materials are crucial for soft electronics,enabling large-area and scalable fabrication,high device density,and good mechanical compliance.Conducting polymers are inherently stretchable and conductive.They can be precisely synthesized from vastly available building blocks,and thus they provide a fruitful platform for fabricating soft electronics.However,amorphous bulk-phase conducting polymers typically exhibit poor mechanical and electrical characteristics.Consequently,it is highly desirable to develop novel engineering approaches to overcome the intrinsic limitations of conducting polymers.In recent years,numerous engineering strategies have been developed to enhance their performances in soft electronic devices via constructing various nanostructures.In this review,we first summarize several unique methodologies to fabricate conducting polymer-based nanostructures.We then discuss how nanoscale engineering approaches can improve several crucial parameters,including electrical conductivity,stretchability,sensitivity,and self-healing property of conducting polymers.Moreover,we also discuss device-level integration of conducting polymer-based nanostructures with other materials for applications in skin-inspired electronics and bio-integrated electronics.Finally,we provide perspectives on challenges and future directions in engineering nanostructured conducting polymers for soft electronics.

Fully Conjugated Ladder Polymers as Metal-Free Photocatalysts for Visible-Light-Driven Water Oxidation

Green plants and algae utilize complicated yet delicate structures to oxidize water into molecular oxygen while releasing electrons for dark reactions.The photocatalytic water oxidation reaction in photosystem Ⅱ is challenging as it Involves in transferring multiple electrons and protons and requires a large overpotential.Herein,for the first time,we report that conjugated ladder polymers with suitable band structures are potential metal-free photocatalysts for efficient and stable water oxidation.Two structurally similar conjugat-ed ladder polymers are synthesized via the condensation reaction between amine-and ketone-containing monomers.Photocatalytic tests reveal that different polymer structures exhibit different photocatalytic performances which are determined by their inherent optoelectronics properties.Meanwhile,our first-principles calculations confirm that photocatalytic water oxidation is thermodynamically feasible for both conjugated ladder polymers under visible light irradiation.Our study unveils a novel class of polymer materials for the water oxidation reaction and further indicates that metal-free photocatalysts hold great potential for future solar-to-chemical conversion.

Integrating bimetallic AuPd nanocatalysts with a 2D aza-fused π-conjugated microporous polymer for light-driven benzyl alcohol oxidation

Efficient catalytic system with low energy consumption exhibits increasing importance due to the upcoming energy crisis.Given this situation,it should be an admirable strategy for reducing energy input by effectively utilizing incident solar energy as a heat source during catalytic reactions.Herein,aza-fused7 r-conjugated microporous polymer(aza-CMP)with broad light absorption and high photothermal conversion efficiency was synthesized and utilized as a support for bimetallic AuPd nanocatalysts in light-driven benzyl alcohol oxidation.The AuPd nanoparticles anchored on aza-CMP(aza-CM P/Au_xPdy)exhibited excellent catalytic performance for benzyl alcohol oxidation under 50 mW/cm^2 light irradiation.The improved catalytic performance by the aza-CMP/Au_xPdy is attributed to the unique photothermal effect induced by aza-CMP,which can promote the catalytic benzyl alcohol oxidation occurring at Au Pd.This work presents a novel approach to effectively utilize solar energy for conventional catalytic reactions through photothermal effect.

Amorphous nickel-iron oxides/carbon nanohybrids for an efficient and durable oxygen evolution reaction

Highly efficient and durable water oxidation electrocatalysts are critically important in a wide range of clean energy technologies,including water electrolyzers and rechargeable metal-air batteries.Here,we report a novel sonochemical approach to synthesize amorphous nickel-iron oxides/carbon nanohybrids with tunable compositions for the oxygen evolution reaction （OER）.The sonochemically synthesized amorphous electrocatalysts with optimal composition exhibit a low overpotential of 290 mV at 10 mA＆#183;cm-2 and a Tafel slope of 31 mV＆#183;decade-1 in a 0.1 M KOH electrolyte,outperforming the benchmark RuO2 catalyst.Meanwhile,these nanohybrids are also highly stable and remain amorphous even after prolonged cycling.In addition to amorphism,sonochemistry endows as-prepared nickel-iron oxides/carbon nanohybrids with a simultaneously formed carbon scaffold and internal Ni（0）,which can enhance the stability and activity for the OER.This work demonstrates that sonochemistry is a unique method for synthesizing amorphous metal oxides toward an efficient and durable OER.

A facile template approach for the synthesis of mesoporous Fe3C/Fe-N- doped carbon catalysts for efficient and durable oxygen reduction reaction

Facile synthetic approaches toward the development of efficient and durable nonprecious metal catalysts for the oxygen reduction reaction （ORR） are very important for commercializing advanced electrochemical devices such as fuel cells and metal-air batteries. Here we report a novel template approach to synthesize mesoporous Fe-N-doped carbon catalysts encapsulated with Fe3C nanoparticles. In this approach, the layer-structured FeOCI was first used as a template for the synthesis of a three- dimensional polypyrrole （PPy） structure. During the removal of the FeOCI template, the Fe^3＋ can be absorbed by PPy and then converted into Fe3C nanoparticles and Fe-N-C sites during the pyrolyzing process. As a result, the as-prepared catalysts could exhibit superior electrocatalytic ORR performance to the commercial Pt/C catalyst in alkaline solutions. Furthermore, the Zn-air battery assembled using the mesoporous carbon catalyst as the air electrode could surpass the commercial Pt/C catalyst in terms of the power density and energy density.

γ-射线辐照法制备具有良好应力检测灵敏度的石墨烯海绵材料（英文）

石墨烯海绵具有优异的机械弹性和电导率,其电导率在石墨烯片相互交联形成的多孔结构被压缩和释放的过程中会发生可逆变化,因此可作为压阻传感器的敏感材料.然而,由于制备方法的限制使得目前报道的石墨烯海绵的压缩模量较大,在检测低应力时材料的电导率变化不明显,导致压阻传感器的灵敏度和检测限不足.本文利用γ射线辐照还原法提供的温和、清洁的还原条件,制备了压缩模量低的石墨烯海绵.其作为压敏传感器的敏感材料,实现了应变灵敏度系数为1.03 kPa-1,检测限低至10 Pa、机械稳定性优异(在50%应变下800次循环最大应力保持76%)的压阻传感器.