Multiple active components synergistically driven heteroatom-doped porous carbon as high-performance counter electrode in dye-sensitized solar cells

A facile template-free in situ self-activation approach for the multiple active components synergistically driven porous carbon was presented via a feasible annealing process.The biomass-derived carbon without additional activation reagents was fabricated using K-rich pomelo peel(PP)as the carbon source,which possesses a high electric conductivity where abundant functional hetero-metal atoms are doped into the carbon framework that playing the role of catalytic graphitization.The K^+that exists within the biomass can induce self-activation during pyrolysis apart from the activating gases during the pyrolysis process.The resulting electrocatalyst of PP-850(PP was pyrolyzed at 850°C in an N_2atmosphere)with abundant heteroatoms possesses a higher power conversion efficiency(PCE)of 7.81%as the counter electrode(CE)of dye-sensitized solar cells(DSCs)compared with the CEs calcinated at other temperatures and a similar PCE with Pt counterpart(8.24%)based on the liquid I_3^-/I^-electrolyte.The better electrocatalytic performance is attributed to the synergistic effect between self-activation and the co-doping of nitrogen,sulfur and phosphorus all together in a carbon matrix.Due to the feasibility of large-scale production,rich heteroatom doping,the PP-derived carbon,which simplifies the procedure and decreases the cost,has a potential application for an alternative electrocatalyst for high-performance photovoltaic devices.

Polyaniline-based electrocatalysts through emulsion polymerization:Electrochemical and electrocatalytic performances

One of the major challenges associated with fuel cells is the design of highly efficient electrocatalysts to reduce the high overpotential of the oxygen reduction reaction (ORR). Here we report Polyaniline (PANI) based micro/nanomaterials with or without transition metals, prepared by the emulsion polymerization and subsequent heat treatment. PANI microspheres with the diameter of about 0.7 mu m have been prepared in basic (NH3 solution) condition, using two different types of surfactant (CTAB, SDS) as the stabilizer, ammonium persulphate (APS) as oxidant with aniline/surfactants molar ratio at 1/1 under the hydrothermal treatment. PANI nanorods, Fe-PANI, and Fe-Co-PANI have been synthesized in acidic (HCI) medium with aniline/surfactants molar ratio at 1/2 and polymerization carried out without stirring for 24 h. Products mainly Fe-Co-PANI have shown high current density with increasing sweep rate and excellent specific capacitance 1753 F/g at the scan rate of 1 mV/s. Additionally, it has shown high thermal stability by thermogravimetric analysis (TGA). Fe-PANI has been investigated for excellent performance toward ORR with four electron selectivity in the basic electrolyte. The PANI-based catalysts from emulsion polymerization demonstrate that the method is valuable for making non-precious metal heterogeneous electrocatalysts for ORR or energy storage and conversion technology. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.

Molten salt as ultrastrong polar solvent enables the most straightforward pyrolysis towards highly efficient and stable single-atom electrocatalyst

Currently,pyrolysis as the most widely used method still has some key issues not well resolved for synthesis of carbon-supported single-atom catalysts(C-SACs),e.g.,the sintering of metal atoms at high temperature as well as the high cost and complicated preparations of precursors.In this report,molten salts are demonstrated to be marvellous medium for preparation of C-SACs by pyrolysis of small molecular precursors(ionic liquid).The ultrastrong polarity on one hand establishes robust interaction with precursor and enables better carbonization,resulting in largely enhanced yield.On the other hand,the aggregation of metal atoms is effectively refrained while no nanoparticle or cluster is formed.By this strategy,a C-SAC with atomically dispersed Fe-N_(4) sites and a high specific area over 2000 m^(2) g^(-1) is obtained,which illustrates high ORR activity in both acid and alkaline media.Moreover,this SAC exhibits superior methanol tolerance and stability after acid soaking at 85℃ for 48 h.It is believed that the molten-salts-assisted pyrolysis can be developed into a routine strategy as it not only can largely simply the synthesis of C-SACs,but also can be extended to prepare other types of SACs.

无机金属纳米材料在生物成像和光热治疗中的研究进展

光热治疗(photothermal therapy, PTT)具有无创性、选择性高以及毒副作用低等优点,是生物医学领域重要的肿瘤治疗方法. PTT的关键在于找到良好的光热转化剂.金属基纳米材料由于较高的光热转化效率和可调控的表面结构,在该疗法中表现出巨大潜力.同时,某些金属基纳米材料还可作为造影剂用于生物成像,对肿瘤进行诊断和监测,指导PTT对肿瘤进行精确热消融,实现肿瘤的诊疗一体化.本文阐述了无机金属基纳米材料在生物成像中的应用,归纳了金基、铋基和过渡金属基纳米光热转化剂的研究现状,分析了PTT在临床转化中存在的问题和解决策略.最后,对金属基纳米材料在生物成像和光热治疗中的未来发展进行了展望.

Theory-oriented screening and discovery of advanced energy transformation materials in electrocatalysis

Various metal-based electrocatalysts from nanocrystals,to clusters and single-atoms,have been well-discovered towards high-efficient power devices and electrocatalytic conversion.To accelerate energy transformation materials discovery,developing high-throughput DFT calculations and machine-learning techniques is of great necessity.This review comprehensively outlines the latest progress of theory-guided design of advanced energy transformation materials.Especially,we focus on the study of single atoms in various power devices,such as fuel cell(oxygen reduction reaction,ORR;acid oxidation reaction;alcohol oxidation reaction),and other reactions for energy-related electrocatalytic conversion of small molecules,such as H_(2)O_(2)evolution reactions(2e−ORR),water splitting(H_(2)evolution reaction/O_(2)evolution reaction,HER/OER),N2 reduction reaction(NRR),and CO_(2)reduction reactions(CO_(2)RR).Firstly,the electronic structure,interaction mechanism,and reaction activation path are discussed to provide an overall blueprint in electrocatalysis and batteries mentioned above.Thereafter,the experimental synthesis strategies,structural recognition,and electrocatalytic performance for the advanced energy transformation materials are figured out.Finally,some viewpoints into the current issues and future design concept of the advanced energy transformation materials are provided.

Tuned single atom coordination structures mediated by polarization force and sulfur anions for photovoltaics

Impeding high temperature sintering is challengeable for synthesis of carbon-supported single-atom catalysts (C-SACs), which requires high-cost precursor and strictly-controlled procedures. Herein, by virtue of the ultrastrong polarity of salt melts, sintering of metal atoms is effectively suppressed. Meanwhile, doping with inorganic sulfur anions not only produces sufficient anchoring sites to achieve high loading of atomically dispersed Co up to 13.85 wt.%, but also enables their electronic and geometric structures to be well tuned. When served as a cathode catalyst in dye-sensitized solar cells, the C-SAC with Co-N4-S2 moieties exhibits high activity towards the iodide reduction reaction (IRR), achieving a higher power conversion efficiency than that of conventional Pt counterpart. Density function theory (DFT) calculations revealed that the superior IRR activity was ascribed to the unique structure of Co-N4-S2 moieties with lower reaction barriers and moderate binding energy of iodine on the Co center, which was beneficial to I2 dissociation.