Nitrogen-doped porous carbon sphere supported Pt nanoparticles for methanol and ethanol electro-oxidation in alkaline media

Mesoporous Carbon Composites Containing Carbon Nanostructures: Recent Advances in Synthesis and Applications in Electrochemistry

Carbon nanostructures (CNs) are various low-dimensional allotropes of carbon that have attracted much scientific attention due to their interesting physicochemical properties. It was quickly discovered that the properties of CNs can be significantly improved by modifying their surface or synthesizing composites containing CNs. Composites combine two or more materials to create a final material with enhanced properties compared with their initial components. In this review, we focused on one group of carbon materials-composites containing CNs (carbon/CN composites), characterized by high mesoporosity. Particular attention was paid to the type of synthesis used, divided into hard- and soft-templating methods, the type of polymer matrix precursors and their preparation method, heteroatom doping, pore formation methods, and correlations between the applied experimental conditions of synthesis and the structural properties of the composite materials obtained. In the last part, we present an updated summary of the applications of mesoporous composites in energy storage systems, supercapacitors, electrocatalysis, etc. The correlations among porous structures of materials, heteroatom doping, and electrochemical or catalytic efficiency, including activity, selectivity, and stability, were also emphasized. To our knowledge, a single review has never summarized pyrolyzed mesoporous composites of polymer-CNs, their properties and applications in electrochemistry.

Poly (3, 4-propylenedioxythiophene)/Hollow carbon sphere composites supported Pt NPs to facilitate methanol oxidation reactions

Direct methanol fuel cells (DMFCs) are thought of as portable, sustainable, and non-polluting energy devices. The exploration of efficient and affordable catalysts for the methanol oxidation reaction (MOR) is significant for the industrial application of DMFCs. In this study, nitrogen-doped hollow carbon spheres (HCS) derived from polydopamine were proposed for the catalyst support for platinum nanoparticles (Pt NPs) for serving as the anode catalyst for DMFCs, and a composite support material was fabricated by in-situ oxidation of 3,4-ethylenedioxythiophene (ProDOT) with HCS to get core-shell structured poly(3,4-propylenedioxythiophene) (PProDOT)-embellished hollow carbon spheres (HCS) (PProDOT/HCS) for further improving the catalytic activity for supported catalyst. The results indicated that the platinum (Pt) on the surface of HCS was well dispersed, and the Pt became smaller and more evenly distributed with the introduction of PProDOT. Simultaneously, the Schottky junction formed between PProDOT and Pt NPs contributes to enhanced charge transfer and catalytic activity of the catalyst. Notably, the core-shell structure of the ternary catalyst, its excellent charge transfer capability, and the interaction between platinum and the support contribute to its high electrocatalytic activity. Electrochemical tests demonstrated that the PProDOT/HCS/Pt catalyst exhibited a mass activity of 1169.6 mA mg-1Pt for methanol oxidation in acidic electrolytes, surpassing the activity of the HCS/Pt catalyst (472.4 mA mg-1Pt) and commercial Pt/C (281.0 mA mg-1Pt).

Ultraviolet Photodetector Based on Poly(3,4-Ethylenedioxyselenophene)/ZnO Core-Shell Nanorods p-n Heterojunction

In this work, we successfully assembled an organic-inorganic core-shell hybrid p-n heterojunction ultraviolet photodetector by the electropolymerization deposition of poly(3,4-ethylenedioxyselenophene) (PEDOS) on the surface of zinc oxide nanoarrays (ZnO NRs). The structures of composite were confirmed by FTIR, UV-Vis, XRD and XPS. Mott-Schottky analysis was used to study the p-n heterojunction structure. The photodetection properties of ZnO NRs/PEDOS heterojunction ultraviolet photodetector were systematically investigated current-voltage (I-V) and current-time (I-t) analysis under different bias voltages. The results showed that PEDOS films uniformly grew on ZnO NRs surface and core-shell structure was formed. The p-n heterojunction structure was formed with strong built-in electric field between ZnO NRs and PEDOS. Under the irradiation of UV light, the device showed a good rectification behavior. The responsivity, detection rate and the external quantum efficiency of the ultraviolet photodetector reached to 247.7 A/W, 3.41 × 10¹² Jones and 84,000% at 2 V bias, respectively. The rise time (τ_r) and fall time (τ_f) of ZnO NRs/PEDOS UV photodetector were obviously shortened compared to ZnO UV photodetector. The results show that the introduction of PEDOS effectively improves the performance of the UV photodetector.