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[Display omitted] Lignin upgrading to various functional products is promising to realize high-value utilization of low-cost and renewable biomass waste, but is still in its infancy. Herein, using industry waste lignosulfonate as the biomass-based carbon source and urea as the dopant, we constructed a heteroatom-doped porous carbon nanosheet structure by a simple NaCl template-assisted pyrolytic strategy. Through the synergistic effect of the NaCl template and urea, the optimized lignin-derived porous carbon catalyst with high content of active nitrogen species and large specific surface area can be obtained. As a result, the fabricated catalysts exhibited excellent electrocatalytic oxygen reduction activity, as well as good methanol tolerance and stability, comparable to that of commercial Pt/C. Moreover, rechargeable Zn-air batteries assembled with this electrocatalyst have a peak power density of up to 150 mW cm-2 and prominent long-term cycling stability. This study offers an inexpensive and efficient way for the massive production of highly active metal-free catalysts from the plentiful, inexpensive and environmentally friendly lignin, offering a good direction for biomass waste recycling and utilization. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe 3 O 4 /Cu 2 O-Ag nanocomposites (NCs) were designed and synthesized successfully. • We realized integration of SERS detection and photocatalytic degradation for PAHs. • Effect of Ag contents on SERS and catalytic activity of Fe 3 O 4 /Cu 2 O-Ag was studied. • SERS detection limit of Fe 3 O 4 /Cu 2 O-Ag towards PAHs was as low as 10-9 to 10-10 M. • Photocatalytic mechanism of PAHs degradation by Fe 3 O 4 /Cu 2 O-Ag was proposed. Polycyclic aromatic hydrocarbons (PAHs) with carcinogenic, teratogenic and mutagenic properties are persistent organic pollutants in the environment. Herein, the novel multifunctional Fe 3 O 4 /Cu 2 O-Ag nanocomposites (NCs) have been established for ultra-sensitive surface-enhanced Raman scattering (SERS) detection and visible light-driven photocatalytic degradation of PAHs. Fe 3 O 4 /Cu 2 O-Ag NCs with different amounts of Ag nanocrystals were synthesized, and the effect of Ag contents on SERS performance was studied by finite-difference time-domain (FDTD) algorithm. The synergistic interplay of electromagnetic and chemical enhancement was responsible for excellent SERS sensitivity of Fe 3 O 4 /Cu 2 O-Ag NCs. The limit of detection (LOD) of optimal SERS substrates (FCA-2 NCs) for Nap, BaP, Pyr and Ant was as low as 10-9, 10-9, 10-9 and 10-10 M, respectively. The SERS detection of PAHs in actual soil environment was also studied. Moreover, a simple SERS method was used to monitor the photocatalytic process of PAHs. The recovery and reuse of Fe 3 O 4 /Cu 2 O-Ag NCs were achieved through magnetic field, and the outstanding SERS and photocatalytic performance were still maintained even after eight cycles. This magnetic multifunctional NCs provide a unique idea for the integration of ultra-sensitive SERS detection and efficient photocatalytic degradation of PAHs, and thus will have more hopeful prospects in the field of environmental protection. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe 3 O 4 /Cu 2 O-Ag nanocomposites (NCs) were designed and synthesized successfully. • We realized integration of SERS detection and photocatalytic degradation for PAHs. • Effect of Ag contents on SERS and catalytic activity of Fe 3 O 4 /Cu 2 O-Ag was studied. • SERS detection limit of Fe 3 O 4 /Cu 2 O-Ag towards PAHs was as low as 10-9 to 10-10 M. • Photocatalytic mechanism of PAHs degradation by Fe 3 O 4 /Cu 2 O-Ag was proposed. Polycyclic aromatic hydrocarbons (PAHs) with carcinogenic, teratogenic and mutagenic properties are persistent organic pollutants in the environment. Herein, the novel multifunctional Fe 3 O 4 /Cu 2 O-Ag nanocomposites (NCs) have been established for ultra-sensitive surface-enhanced Raman scattering (SERS) detection and visible light-driven photocatalytic degradation of PAHs. Fe 3 O 4 /Cu 2 O-Ag NCs with different amounts of Ag nanocrystals were synthesized, and the effect of Ag contents on SERS performance was studied by finite-difference time-domain (FDTD) algorithm. The synergistic interplay of electromagnetic and chemical enhancement was responsible for excellent SERS sensitivity of Fe 3 O 4 /Cu 2 O-Ag NCs. The limit of detection (LOD) of optimal SERS substrates (FCA-2 NCs) for Nap, BaP, Pyr and Ant was as low as 10-9, 10-9, 10-9 and 10-10 M, respectively. The SERS detection of PAHs in actual soil environment was also studied. Moreover, a simple SERS method was used to monitor the photocatalytic process of PAHs. The recovery and reuse of Fe 3 O 4 /Cu 2 O-Ag NCs were achieved through magnetic field, and the outstanding SERS and photocatalytic performance were still maintained even after eight cycles. This magnetic multifunctional NCs provide a unique idea for the integration of ultra-sensitive SERS detection and efficient photocatalytic degradation of PAHs, and thus will have more hopeful prospects in the field of environmental protection. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydrothermal and sol-gel method were combined to prepare carbon microspheres. • Carbon microspheres with multi-layer dendritic hollow structure, high specific surface area and abundant micropores were successfully prepared. • Excellent cycle stability and great specific capacitance were obtained by the supercapacitor prepared from the carbon microspheres. The electrochemical properties of corn starch (CS)-based hydrothermal carbon microsphere (CMS) electrode materials for supercapacitor are closely related to their structures. Herein, cetyltrimethyl ammonium bromide (CTAB) was used as a soft template to form the corn starch (CS)-based carbon microspheres with radial hollow structure in the inner and middle layers by hydrothermal and sol-gel method. Due to the introduction of multi-layer hollow structure of carbon microsphere, more micropores were produced during CO 2 activation, which increased the specific surface area and improved the capacitance performance. Compared to commercial activated carbon, the four different morphologies of corn starch CMS had better electrochemical performances. Consequently, the proposed CO 2 –(CTAB)-CS-CS exhibits a high discharge specific capacitance of 242.5F/g at 1 A/g in three-electrode system with 6 M KOH electrolyte, better than commercial activated carbon with 208.5F/g. Moreover, excellent stability is achieved for CO 2 –(CTAB)-CS-CS with approximately 97.14 % retention of the initial specific capacitance value after 10,000 cycles at a current density of 2 A/g, while the commercial activated carbon has 86.96 % retention. This implies that the corn starch-based multilayer hollow CMS could be a promising electrode material for high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

[Display omitted] • SERS platform was designed by introducing secondary enhanced Au@Ag NPs on GO-AuNS. • Multi-dimensional plasmonic coupling occurs in vertical and horizontal directions. • SERS platform exhibits ultrasensitive SERS detection and enrichment capabilities. • SERS platform has a linear SERS response and low detection limit of 10−11 M for BR. Rapid and sensitive detection of free bilirubin (BR) is essential for early diagnosis of jaundice and other hepatobiliary diseases. Inspired by sandwich immunoassay strategy, a multi-dimensional plasmonic coupling SERS platform composed of graphene oxide-Au nanostars nanocomposites (GANS NCs) and Au@Ag nanoparticles (NPs) was designed for label-free detection of BR. Specifically, GANS NCs were first prepared, and their excellent SERS activity was ascribed to synergistic enhancement effect of electromagnetic enhancement and chemical enhancement. Furthermore, SERS spectroscopy was used to monitor the adsorption process of BR. Subsequently, secondary reinforcing Au@Ag NPs were directly added, ultimately resulting in a multi-dimensional plasmonic coupling effect. The SERS enhancing mechanism of coupled system was discussed through electromagnetic field simulations. Interestingly, the high-density hotspots generated by strong plasmonic coupling in GANS-Au@Ag substrate could lead to more extraordinary SERS enhancing behavior compared to GANS NCs. Sensing efficiency of the SERS platform was examined by BR with a detection limit down to 10−11 M. Besides, GANS-Au@Ag NCs performed high uniformity and reproducibility. This work not only opens up a new avenue for construction of multi-dimensional plasmonic coupling system, but also offers a new biosensing technology for label-free diagnosis of BR-related diseases, thereby expecting to be applied in clinical diagnosis. [ABSTRACT FROM AUTHOR]

[Display omitted] • A SERS platform for simultaneous detection of E. coli and S. aureus was developed. • A dual SERS enhancement strategy based on sandwich-like structure was applied. • Aptamers modified-Fe 3 O 4 @SiO 2 -Au NCs were used for bacterial capture and isolation. • GO-Au NSs functionalized with DTNB/4-MBA and aptamers were proposed as SERS tags. • The detection limit for E. coli and S. aureus was as low as 10 cfu/mL. In this work, a novel surface-enhanced Raman scattering (SERS) sandwich strategy biosensing platform has been established for simultaneously detecting Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Fe 3 O 4 @SiO 2 -Au nanocomposites (NCs) with varying amounts of Au nanocrystals were prepared, and the effect of interparticle gaps on SERS activity was studied by finite-difference time-domain (FDTD) method. The optimal magnetic SERS-active substrates (FS-A5) were functionalized with the specific aptamers to act as capture probes. Meanwhile, graphene oxide-Au nanostars (GO-Au NSs) decorated with Raman reporters and aptamers were used as SERS tags. The loading density of Au NSs on GO was tuned to change the number of SERS active sites. In this proposal, E. coli and S. aureus were first captured by capture probes and then bound with SERS tags to form a sandwich-like structure, which caused enhanced electromagnetic field because of the dual enhancement strategy. Under optimal conditions, SERS platform could detect E. coli and S. aureus simultaneously, and the detection limit was as low as 10 cfu/mL. Our sandwich assay-based dual-enhanced SERS platform provides a new idea for simultaneously detecting multiple pathogens with high selectivity and sensitivity, and thus will have more hopeful prospects in the field of food safety. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Herein, we report a novel nanocomposite consisting of n-type Sn-doped hematite and p-type CaMn 2 O 4 nanowire (CaMn 2 O 4 /α-Fe 2 O 3). The nanocomposite was characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), ultraviolet-visible absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), which showed that nanospindle-like Sn-doped hematite and CaMn 2 O 4 nanowire contact intimately in the nanocomposite, resulting in efficient charge transfer and separation. Photoelectrochemical results reveal that the nanocomposite possesses higher donor density, enhanced conductivity and lower overpotential for dioxygen evolution. In addition, the nanocomposite demonstrates high photocatalytic activity for water oxidation to produce oxygen in a photoelectrochemical cell. The amount of O 2 evolved from the optimized photoanode of the photoelectrochemical cell was 1.98 μmol in 2 h of simulated sunlight irradiation. This work demonstrates a facile synthesis of a novel nanocomposite as anode material for photocatalytic water oxidation to produce O 2. [ABSTRACT FROM AUTHOR]

Described herein is the synthesis, characterization and photoelectrochemical behavior of a novel composite consisting of nanolayered manganese-calcium oxide (MCO) and mesoporous tungsten trioxide (WO 3 ). The samples were characterized by transmission electron microscopy (TEM), and X-ray diffraction (XRD). The results demonstrated that superior interfacial contacts had been formed between WO 3 and MCO. UV–vis diffuse reflectance spectroscopy (DRS), photoelectrochemical characterization, and incident photon-to-current efficiency (IPCE) revealed an enhanced light harvesting and effective electron-hole separation. A photoelectrochemical (PEC) cell composed of the n-type MCO/WO 3 as a photoanode and platinum sheet as a counter electrode was assembled to estimate the feasibility for overall water splitting under a solar simulator illumination. The photocatalytic hydrogen and oxygen production from the photochemical cell with optimized photocatalyst (MCO/WO 3 -9) under 2 h simulated solar light irradiation was 1.9 μmol and 0.7 μmol, respectively, at low extra bias (0.90 V vs. RHE). Our investigation suggests that coupling MCO with n-type semiconductor WO 3 as photoanode is a promising method to improve the activity of overall water splitting to generate oxygen and hydrogen. [ABSTRACT FROM AUTHOR]