Thiocyanogen-modulated N, S Co-doped lignin hierarchical porous carbons for high-performance aqueous supercapacitors.

Constructing heteroatom-doped porous carbons with distinct charge storage properties is significant for high-energy-density supercapacitors, yet it remains a formidable challenge. Herein, we employed a thiocyanogen-modulated alkali activation strategy to synthesize N and S co-doped lignin hierarchical porous carbon (NSLHPC). In this process, thiocyanogen serves as a surface modulation mediator to substitute oxygen with nitrogen and sulfur species, while the combination of KOH activation and MgO template generates numerous nanopores within the carbon structure. The three-dimensional interconnected nanosheet architecture facilitates rapid ion transfer and enhances accessibility to active sites. Density functional theory (DFT) calculations demonstrate that introducing N and S heteroatoms through oxygen substitution reduces the adsorption energy barrier of Zn2+. Consequently, the optimized NSLHPC exhibits a remarkable specific capacitance of 438F/g at 0.5 A/g in 6 M KOH, delivering an energy density of 10.4 Wh/kg in the symmetric supercapacitor and an impressive energy density of 104.9 Wh/kg in the zinc-ion hybrid capacitor. The NSLHPC cathode also shows an excellent lifespan with capacitance retention of 99.0 % and Columbic efficiency of 100 % over 10,000 cycles. This study presents innovative strategies for engineering high-performance porous carbon electrode materials by emphasizing pore structure modulation and N, S co-doping as crucial approaches.

Self-assembled high polypyrrole loading flexible paper-based electrodes for high-performance supercapacitors.

Despite the intriguing features of freestanding flexible electronic devices, such as their binder-free nature and cost-effectiveness, the limited loading capacity of active material poses a challenge to achieving practical high-performance flexible electrodes. We propose a novel approach that integrates multiple self-assembly and in-situ polymerization techniques to fabricate a high-loading paper-based flexible electrode (MXene/Polypyrrole/Paper) with exceptional areal capacitance. The approach enables polypyrrole to form a porous conductive network structure on the surface of paper fiber through MXene grafting via hydrogen bonding and electrostatic interaction, resulting in an exceptionally high polypyrrole loading of 10.0 mg/cm2 and a conductivity of 2.03 S/cm. Moreover, MXene-modified polypyrrole paper exhibits a more homogeneous pore size distribution ranging from 5 to 50 µm and an increased specific surface area of 3.11 m2/g. Additionally, we have optimized in-situ polymerization cycles for paper-based supercapacitors, resulting in a remarkable areal capacitance of 2316 mF/cm2 (at 2 mA/cm2). The capacitance retention rate and conductivity rate maintain over 90 % after undergoing 100 bends.The maximum energy density and cycling stability are characterized to be 83.6 µWh/cm2 and up to 96 % retention after 10,000 cycles. These results significantly outperform those previously reported for paper-based counterparts. Overall, our work presents a facile and versatile strategy for assembling high-loading, paper-based flexible supercapacitors network architecture that can be employed in developing large-scale energy storage devices.

Preparation and Photovoltaic Performance of a Composite TiO2 Nanotube Array/Polyaniline UV Photodetector.

TiO2 has great potential for application in UV photodetectors due to its excellent photoelectric response. In this work, composite nanomaterials of TiO2 nanotube arrays (TiO2 NTAs) and polyaniline (PANI) were successfully prepared on titanium sheets using an anodic oxidation electrochemical method. The results showed that the TiO2 NTA/PANI composite materials had excellent UV photosensitivity and responsiveness and good stability and reproducibility. This was mainly attributed to the p-n heterostructure formed inside the TiO2 NTA/PANI composites that hindered the recombination of photogenerated electron-hole pairs and improved their utilization of UV light. This work provides a theoretical basis for the application of metal oxides in UV photodetectors, which is important for the development of UV photodetectors.

Preparation of ZnO Nanosheet Array and Research on ZnO/PANI/ZnO Ultraviolet Photodetector.

High-performance ultraviolet photodetectors have important scientific research significance and practical application value, which has been the focus of researchers. In this work, we have constructed a highly photosensitive UV photodetector with a unique "sandwich" structure, which was mainly composed of two layers of ZnO nanosheet arrays and one layer of polyaniline (PANI). The results showed that the UV current of ZnO/PANI devices was 100 times higher than that of pure ZnO devices under the same UV irradiation time. At a 365 nm wavelength, the device had excellent photocurrent responsiveness and photoconductivity. This high performance was attributed to the large specific surface area of ZnO nanosheets and the p-n junction formed between P-type PANI nano-porous film and N-type ZnO nanosheets. This provides a solid theoretical basis for the application of ZnO nanosheets in ultraviolet detection, and possesses significance for the development of ultraviolet photodetectors.

Boosting capacitive performance of N, S co-doped hierarchical porous lignin-derived carbon via self-assembly assisted template-coupled activation.

Heteroatom-doped porous carbon materials show promise for use as supercapacitor electrodes, but the tradeoff between surface area and the heteroatom dopant levels limits the supercapacitive performance. Here, we modulated the pore structure and surface dopants of N, S co-doped hierarchical porous lignin-derived carbon (NS-HPLC-K) via self-assembly assisted template-coupled activation. The ingenious assembly of lignin micelles and sulfomethylated melamine into a magnesium carbonate basic template greatly promoted the KOH activation process, which endowed the NS-HPLC-K with uniform distributions of activated N/S dopants and highly accessible nanosized pores. The optimized NS-HPLC-K exhibited a three-dimensional hierarchically porous architecture composed of wrinkled nanosheets and a high specific surface area of 2538.3 ± 9.5 m2/g with a rational N content of 3.19 ± 0.01 at.%, which boosted the electrical double-layer capacitance and pseudocapacitance. Consequently, the NS-HPLC-K supercapacitor electrode delivered a superior gravimetric capacitance of 393 F/g at 0.5 A/g. Furthermore, the assembled coin-type supercapacitor showed good energy-power characteristics and cycling stability. This work provides a novel idea for designing eco-friendly porous carbons for use in advanced supercapacitors.

Nitrogen-rich accordion-like lignin porous carbon via confined self-assembly template and in-situ mild activation strategy for high-performance supercapacitors.

Nitrogen-doped porous carbons have emerged as promising electrode materials for supercapacitors. However, the precise control of carbon geometry and the effective doping method remain challenging. Herein, a confined self-assembly template and in-situ mild activation strategy is proposed to prepare cubic lignin composite precursor, followed by co-pyrolysis with melamine at a high temperature for nitrogen-doped hierarchical porous carbons (N-HPLCs). The zinc oxalate template has the coupling effect of confinement and mild activation during carbonization, which not only prevents the restacking of the carbon matrix but also generates zinc cyanamide intermediate to avoid excessive loss of nitrogen species. The optimized N-HPLCs exhibit an accordion-like framework with interconnected porous sheets, ultrahigh edge-nitrogen doping level (up to 12.20 at.%), and a total nitrogen doping level of 14.09 at.%. Consequently, it shows a high gravimetric capacitance of 354 F/g at 0.2 A/g, an extraordinary surface-area-normalized capacitance of 82.1 ± 0.2 µF/cm2, and good rate capability in supercapacitor applications. Moreover, the fabricated coin-type symmetric supercapacitor displays a high energy density of 12.9 Wh/kg at 161.9 W/kg and superior cycling stability with a 99.5% capacitance retention after 16,000 cycles at 2.0 A/g. This work offers a novel method for preparing nitrogen-enriched lignin-derived carbon for high-performance supercapacitors.

Lamellar hierarchical lignin-derived porous carbon activating the capacitive property of polyaniline for high-performance supercapacitors.

Lignin porous carbons show good potential as carbon electrode materials for supercapacitors, but face the problem of low capacitance. Combining lignin porous carbons with polyaniline can achieve high capacitance. However, capacitance degradation resulting from the poor compatibility between lignin porous carbons and polyaniline has been the major obstacle for their application. In this work, three lignin porous carbons with different geometries were used as the hosts to anchor polyaniline for carbon/polyaniline composites via in- situ oxidative polymerization, and the compatibility between lignin porous carbons and polyaniline was investigated. It was determined the lamellar hierarchical lignin porous carbon with crumpled nanosheets can provide a large accessible surface area for the heterogeneous nucleation of aniline, which ensures uniform loading of interpenetrating polyaniline nanofibers. Benefiting from the interpenetrating conductive network and enhanced compatibility, the lamellar hierarchical porous carbon/polyaniline composite possesses a high capacitance of up to 643 F/g at 1.0 A/g and a sufficient capacitance of 390 F/g at 30.0 A/g. This work therefore provides design guidance for carbon hosts in high-performance supercapacitor composite electrodes.

Construction of CoP@C embedded into N/S-co-doped porous carbon sheets for superior lithium and sodium storage.

To improve the electrical conductivity and relief the large volume variation, carbon coated CoP particles were designed to homogeneously embed into porous carbon sheets, which were synthesized though a simultaneous carbonization and phosphorization method. Notably, the uniform carbon shells and porous carbon sheets constructed a tough conductive matrix to enhance the electron transfer and structural stability during charging/discharging processes. Moreover, the heteroatom doping of nitrogen and sulfur could not only introduce more active sites and defects on the carbon sheets, but also increased electrical conductivity. Owing to the unique structure, the obtained material displayed good electrochemical performance for lithium storage (638.8 mA h g-1 at 0.2 A g-1 after 500 cycles and 334.9 mA h g-1 at 10 A g-1) and sodium storage (329.4 mA h g-1 at 0.2 A g-1 after 150 cycles and 162.4 mA h g-1 at 5 A g-1). More importantly, the reaction mechanism and the ion diffusion coefficient were explored by ex-situ XRD and EIS for both LIBs and SIBs. This versatile approach may avail to predigest the tedious phosphating process to obtain high-performance TMPs-based hybrids (such as Ni2P/C) by employing other metal salts.

Controlled preparation of lignin/titanium dioxide hybrid composite particles with excellent UV aging resistance and its high value application.

In this work, a novel lignin/titanium dioxide (QAL/TiO2) hybrid composite with regular microstructure and synergistically enhanced UV absorption properties was synthesized by a simple hydrothermal method using lignin and butyl titanate. The prepared QAL/TiO2 composite is hybrid structure in which lignin and TiO2 is uniformly embedded, and has strong chemical bond bonding force. The QAL/TiO2 hybrid composite particles were used for doping modification of waterborne polyurethane (WPU), which had good interfacial compatibility and dispersibility in WPU. The obtained WPU + QAL/TiO2 film shows excellent UV shielding performance and great mechanical properties, the tensile strength and elongation at break are significantly improved compared with pure WPU film. And it also has excellent anti-UV aging property, that the mechanical performance basically remains unchanged after 96 h of high power ultraviolet irradiation. This work not only provides a kind of lignin/TiO2 hybrid composite with neat structure, good dispersion and excellent optical properties, but also has great significance for the high-valued utilization of biomass resources.