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Herein, three tritopic carboxylic acids were used to construct three Zr-MOFs, HIAM-4033, HIAM-4034, and HIAM-4035, to investigate the effect of carboxyl position on the MOF structures. The results showed that HIAM-4033 and HIAM-4034 possess (3,9)-c models with different underlying nets, whereas HIAM-4035 exhibits the same underlying net as UiO-68. Nanosized HIAM-4033 exhibits excellent sensitivity and selectivity for detecting aromatic acids, such as benzoic acid and 2-fluorobenzoic acid, compared with aliphatic acids and inorganic acids. This study offers new insights into achieving an organic linker directed structure evolution of Zr-MOFs, which might facilitate the discovery of unprecedented underlying nets. [ABSTRACT FROM AUTHOR]

Polychlorinated biphenyls (PCBs) are a class of persistent organic pollutants, which cause serious harm to human health and ecological environment. Thus, a low-cost membrane was developed for highly effective removal and rapid surface-enhanced Raman scattering (SERS) detection of PCBs by filling esterified-sawdust (CA-SD) modified with silver nanoparticles (AgNPs) into solid phase extraction (SPE) column. SD was first modified by an esterification cross-linking strategy and then AgNPs were anchored on the CA-SD to prepare highly sensitive and reproducible SERS substrates (AgNPs/CA-SD). Due to the contraction of the surface area of the CA-SD caused by drying, the gap between the AgNPs could be reduced, thereby generating a large number of hot spots and driving more target molecules into them to obtain the enhanced SERS signals. The AgNPs/CA-SD-based SPE membrane showed excellent SERS activity with an enhancement factor of 5.98 × 108 for the R6G analysis. The proposed SERS-active SPE membrane with functionalization of mercapto-β-cyclodextrin was further developed for the determination of PCB-77 and PCB-1 with the LODs of 1.43 × 10−9 M and 2.12 × 10−8 M, respectively. In addition, each PCB in the mixed sample could be quickly distinguished based on the characteristic peaks. The current research exhibits great potential for the simultaneous detection of multiple environmental contaminants and can meet the needs of on-site emergency detection. [Display omitted] • A low-cost sawdust-based SPE membrane was prepared through esterification and modification process. • The membrane could realize enrichment and high-sensitivity SERS detection of PCBs. • The membrane was capable of rapid analysis of the mixed PCBs samples. • This membrane is expected to be used for on-site rapid analysis of water pollution incidents. [ABSTRACT FROM AUTHOR]

The development of nanoscaled luminescent metal–organic frameworks (nano‐LMOFs) with organic linker‐based emission to explore their applications in sensing, bioimaging and photocatalysis is of great interest as material size and emission wavelength both have remarkable influence on their performances. However, there is lack of platforms that can systematically tune the emission and size of nano‐LMOFs with customized linker design. Herein two series of fcu‐ and csq‐type nano‐LMOFs, with precise size control in a broad range and emission colors from blue to near‐infrared, were prepared using 2,1,3‐benzothiadiazole and its derivative based ditopic‐ and tetratopic carboxylic acids as the emission sources. The modification of tetratopic carboxylic acids using OH and NH2 as the substituent groups not only induces significant emission bathochromic shift of the resultant MOFs, but also endows interesting features for their potential applications. As one example, we show that the non‐substituted and NH2‐substituted nano‐LMOFs exhibit turn‐off and turn‐on responses for highly selective and sensitive detection of tryptophan over other nineteen natural amino acids. This work sheds light on the rational construction of nano‐LMOFs with specific emission behaviours and sizes, which will undoubtedly facilitate their applications in related areas. [ABSTRACT FROM AUTHOR]

The development of nanoscaled luminescent metal–organic frameworks (nano‐LMOFs) with organic linker‐based emission to explore their applications in sensing, bioimaging and photocatalysis is of great interest as material size and emission wavelength both have remarkable influence on their performances. However, there is lack of platforms that can systematically tune the emission and size of nano‐LMOFs with customized linker design. Herein two series of fcu‐ and csq‐type nano‐LMOFs, with precise size control in a broad range and emission colors from blue to near‐infrared, were prepared using 2,1,3‐benzothiadiazole and its derivative based ditopic‐ and tetratopic carboxylic acids as the emission sources. The modification of tetratopic carboxylic acids using OH and NH2 as the substituent groups not only induces significant emission bathochromic shift of the resultant MOFs, but also endows interesting features for their potential applications. As one example, we show that the non‐substituted and NH2‐substituted nano‐LMOFs exhibit turn‐off and turn‐on responses for highly selective and sensitive detection of tryptophan over other nineteen natural amino acids. This work sheds light on the rational construction of nano‐LMOFs with specific emission behaviours and sizes, which will undoubtedly facilitate their applications in related areas. [ABSTRACT FROM AUTHOR]

A novel exfoliated NbS 2 nanosheets produced via liquid exfoliation method exhibited an excellent catalytic activity for nitrogen reduction reaction. • A novel exfoliated NbS 2 nanosheets was produced via liquid exfoliation method. • Exfoliated NbS 2 nanosheets exhibited an excellent catalytic activity for NRR. • The Nb4+ species of exfoliated NbS 2 nanosheets was acted as active sites. • Exfoliated NbS 2 nanosheets was acted as the cathode for a Zn-N 2 battery. • Solar-driven NRR-OER device was achieved with exfoliated NbS 2 nanosheets. Electrochemical nitrogen reduction reaction (NRR) under mild conditions is an attractive prospect for ammonia synthesis. However, this process faces with poor ammonia yield rate and low Faradic efficiency. Herein, we developed exfoliated metallic niobium disulfate (NbS 2) nanosheets for an electrochemical NRR. Owing to more exposed active sites and high electron transfer ability, the exfoliated NbS 2 nanosheets show an extraordinary activity for electrochemical NRR. A high Faradaic efficiency of 10.12 % with an ammonia yield rate of 37.58 μg h−1 mg−1 cat is achieved at −0.5 V versus reversible hydrogen electrode (RHE). The Nb4+ species of exfoliated NbS 2 are confirmed as active sites for NRR. When the exfoliated NbS 2 nanosheets are further assembled into a Zn-N 2 battery and serve as the cathode, an energy density of 714 mA h g−1 with a power density of 0.31 mW cm−2 is achieved. Notably, electrochemical NRR on exfoliated NbS 2 nanosheets can be further driven by solar energy. [ABSTRACT FROM AUTHOR]

Development of cost‐effective and highly efficient oxygen evolution reaction (OER) electrocatalysts has become a vital project of renewable energy technologies. The OER is critical for a variety of electrochemical energy devices such as water electrolyzers, metal‐air batteries, CO2 reduction, and electrosynthesis of ammonia. Compared to extensively studied metal oxide catalysts, graphitized carbon catalysts have been newly emerged as promising OER catalysts especially in less corrosive alkaline media, due to their low cost, high electrical conductivity, unique physicochemical properties, and excellent electrocatalytic performances. In this review, we discussed recent advances in nanostructured carbon electrocatalysts. At first, metal‐free OER carbon electrocatalysts including single‐ and multi‐heteroatom doping and edge‐ and defect‐rich defects are introduced. Then, transition metal and heteroatom co‐doped nanocarbons are summarized including Co−N−C, Ni−N−C, and Fe‐N−C. In addition, carbon based hybrid electrocatalysts are highlighted, which include carbon based transition metal nitrides (TMNx), sulfides (TMSx), and selenides (TMSex), and phosphides (TMPx). Finally, current challenges and perspective for future research on carbon‐based OER catalysts are outlined. [ABSTRACT FROM AUTHOR]

Acetylcholinesterase (AChE) is a key hydrolase in the cholinergic system, which directly determines the degradation of neurotransmitters. Therefore, it is a significant challenge to detect AChE in human blood with high sensitivity and selectivity in physiological and pathological processes. A novel nanoprobe by decorating the surface of gold nanoparticles with neostigmine (NE) AuNPs/NE was constructed for the AChE assay in serum. The principle is based on the specific recognition and cleavage of carbamate bonds in AuNPs/NE by AChE to form hydroxyl groups, resulting in changes of SERS spectra. The results show that 10 nm AuNPs/NE exhibit excellent catalytic activity for this reaction and the reaction rate is six times higher than that of 70 nm AuNPs/NE. Benefiting from the combined advantages of catalytic reaction specificity and molecular finger printing provided by SERS technology, AuNPs/NE exhibit high selectivity for AChE. The limit of detection (LOD) of this method for AChE activity was low to 0.02 U/mL. In addition, the spiked recovery of AChE in serum samples was 75.0%–119.2%. The proposed sensor also exhibits long-term stability and high biocompatibility with the increasing incubation time. More importantly, this work provides a new perspective for elucidating the role of AChE regulated by oxidative stress in the pathology of depression. [Display omitted] • A novel nanoprobe by decorating the surface of gold nanoparticles with neostigmine was constructed. • The proposal was based on the specific recognition and cleavage of carbamate bonds in neostigmine with acetylcholinesterase. • The limit of detection of the nanosensor for acetylcholinesterase activity was low to 0.02 U/mL. • The nanosensor can be applied to the susceptible SERS detection of Acetylcholinesterase in blood with high sensitivity. [ABSTRACT FROM AUTHOR]

• A novel Gd3+ doped nanosheet-assembled BiOBr nanospheres was synthesized. • The Gd3+ doped BiOBr exhibited an enhanced photocatalytic activity for CO 2 reduction. • The holes were acted as the main active species in photocatalytic CO 2 reduction. Rising carbon dioxide (CO 2) levels in the atmospheric environment is a key cause of global warming. To reduce the concentration of CO 2 in the atmosphere, converting CO 2 into hydrocarbon fuels is an eye-catching strategy. Herein, we achieve in-situ doping of Gd3+ for BiOBr microspheres consisting of nanosheets via a simple hydrothermal method. The resulting Gd doped BiOBr structure (BiOBr/Gd) exhibits considerable improvement on photocatalytic activities for CO 2 reduction. Compared to bare BiOBr (24.097 μmol g−1 for 3 h), the BiOBr/Gd-0.05 displays excellent performance of CO 2 photoreduction with nearly five-fold increase in the rate of methanol emission (123.711 μmol g−1 for 3 h). The enhanced CO 2 reduction activities of BiOBr/Gd-0.05 are attributed to the mechanism that Gd3+ ions are introduced into the lattice of BiOBr to broaden the visible light response. Furthermore, we discuss the mechanism of photocatalytic CO 2 reduction, where holes are the main active species in the process of CO 2 reduction. [ABSTRACT FROM AUTHOR]