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The growing needs for sustainable and efficient energy sources have heightened interest in electrocatalytic water splitting (EWS), a promising method for hydrogen production as a clean and renewable energy carrier. EWS, which splits water molecules into hydrogen and oxygen, faces efficiency challenges due to the slow kinetics of the oxygen evolution reaction (OER) at the anode and the hydrogen evolution reaction (HER) at the cathode. Developing effective electrocatalysts is essential to overcome these limitations. Among the various electrocatalysts studied, transition metal sulfides (TMSs) have garnered significant attention due to their low cost and abundant active sites. Despite the superior electrochemical performance of TMSs compared to other materials, their inherent low conductivity and sluggish reaction kinetics remain major challenges. Recent advancements have focused on the in situ growth of TMSs on conductive substrates to enhance electron transfer and overall catalytic performance, eliminating the need for polymer binders and improving electrode stability. This review provides an in-depth analysis of the key aspects involved in the synthesis of in situ grown TMS electrodes, including the selection of TMS active materials, various substrates, and preparation strategies. The review then offers a comprehensive overview of different types of in situ grown TMS electrodes, with a focus on the most extensively researched materials: molybdenum sulfides, cobalt sulfides, nickel sulfides, and their composites. Finally, the limitations and future perspectives are discussed, highlighting potential directions for advancing the development of in situ grown TMS catalysts. [ABSTRACT FROM AUTHOR]

Direct ethanol fuel cells (DEFCs), which have been widely recognized as nontoxic and green energy conversion devices, show attractive application prospects for liquid hydrogen-carriers, due to the higher specific energy and lower toxicity of ethanol. Pt-based catalysts are widely used in DEFCs, while their poor poisoning resistance highlights the importance of composition and structure optimization. Herein, we synthesized a series of reduced graphene oxide supported ternary alloy AuxPt1−xCu3/rGO (x = 0-1) catalysts with excellent ethanol oxidation performance and a composition-dependent volcano plot trend of the ordering degree was observed and rationalized. The highest Pt-normalized mass activity of Au0.8Pt0.2Cu3/rGO is attributed to the optimized CO binding energy according to DFT calculations. This work not only provides an efficient EOR catalyst based on ordered alloys AuxPt1−xCu3 (x = 0-1), but also offers valuable insight into the role of a third metal in tuning the structure and function of alloys. [ABSTRACT FROM AUTHOR]

A series of 6-oxo-3-(1,2,4,5-substituted-1H-imidazol-3-ium-3-yl)-3,6-dihydro-1,2,4,5-tetrazin-3-ides (3a–3z, 3aa–3ak) was synthesized with medium to good yield by the reaction of 3,6-dichloro-1,2,4,5-tetrazine with a variety of substituted imidazoles in the presence of trace water in solvents. The quinoidal-like structure of these compounds was demonstrated via spectroscopic methods, X-ray diffraction techniques, and computational chemistry. Additionally, water–18O was used to prove that the oxygen in tetrazinone comes from the water in solvents via high-resolution mass spectrometry (HRMS). Moreover, a possible mechanism of aromatic nucleophilic substitution is proposed. [ABSTRACT FROM AUTHOR]

The misuse and improper handling of norfloxacin (NOR) can cause serious harm; therefore, the sensitive and visual detection of NOR is of great significance. However, it is still a huge challenge to establish the multiplex fluorescence detection of NOR. Herein, four hydrazone-linked covalent organic frameworks (COFs) with different luminescence were prepared using 2,5-bis(2-methoxyethoxy)terephthalohydrazide as the nucleus and aldehyde monomers containing methoxy and different numbers of hydroxyl groups as linkers, respectively, and the precise modulation of the emission of hydrazone-linked COFs was achieved. The intrinsic blue emission of NOR was combined with hydrazone-linked COFs to construct ratiometric fluorescence sensors to monitor NOR. Among them, a two-signal change ratiometric fluorescence sensor based on COFBMTH-HB showed the highest sensitivity, the lowest detection limit (51 ng mL−1) and the widest linear range (153 ng mL−1 to 48 μg mL−1), originating from the lowest background fluorescence and the largest output signal. Based on the obvious color changes in the detection process, a novel test paper was also proposed with simultaneous multi-chroma and was combined with a smartphone App as a real-time detection tool to successfully monitor NOR in real fish samples. This portable paper-based sensor provides support for rapid and simple NOR visual detection. In addition, a two-dimensional code with multiple information encryption was developed by taking advantage of the obvious color changes as well as the excitation dependence of COFBMTH-HB during the detection of NOR, which further broadens the application of two-dimensional codes in the field of anti-counterfeiting. [ABSTRACT FROM AUTHOR]

In this study, an ultrasensitive electrochemical miRNA-21 biosensor is described. Manganese dioxide-gold nanoparticle (MnO2-Au NP) nanoconjugates were employed as sensing base materials, miRNA-21 was selected as a model analyte, and hybridization chain reaction (HCR) was employed to form long DNA concatemers using two different oligonucleotides with a complementary sequence. Thus, lots of biotin were loaded on DNA concatemers and one of them was labelled with biotin at its 3′ terminal. The biosensor was designed as follows: a sulfhydryl-hairpin probe (HP) was first dropped on the surface of the glassy carbon electrode (GCE) modified with MnO2-Au NP nanoconjugates (HP/MnO2-AuNPs/GCE). After it was treated with MCH, the modified electrode was hybridized with miRNA-21, resulting in the loop of HP being opened to form a vertical structure. Subsequently, the modified electrode (miRNA-21/HP/MCH/MnO2-AuNPs/GCE) was incubated with DNA concatemers to form a sandwich structure of HP-miRNA-21-DNA concatemers on the modified electrode surface. Finally, the streptavidin-HRP conjugates were linked to the sandwich structure by specific recognition interaction between biotin and avidin. Differential pulse voltammetry (DPV) was used to measure the electrochemical response of the biosensor in the phosphate-buffered solution (0.10 M PBS, pH 7.0) containing 2.0 mM hydroquinone (HQ) and 1.8 mM H2O2. As a result, a larger reductive signal was obtained at a potential of −0.17 V (vs. SCE). Various experimental conditions were optimized, including solution pH, incubation time, and the amount of DNA concatemers. Under optimal conditions, the biosensor showed good sensing performance, such as a wide linear response range (0.1 fM and 100 nM) and low detection limit (0.063 fM, at S/N = 3). Meanwhile, the biosensor can discriminate single base matched miRNA-21, indicating that the biosensor had good selectivity. [ABSTRACT FROM AUTHOR]

We report the synthesis of a hybrid layered cobalt hydroxide sample and its redox behaviors in the electrochemical oxygen evolution reaction (OER). Compound Co7(OH)12(C2H4S2O6)·1.6H2O was synthesized via a homogeneous alkalization reaction using Co(SO3C2H4SO3) and hexamethylenetetramine. This compound comprises cationic host layers of {[Co7(OH)12]2+}∞, which comprise octahedrally (CoOh) and tetrahedrally (CoTd) coordinated Co cations at a CoOh : CoTd ratio of 5 : 2. The ethane-disulfonate ions are combined with the cationic host layers by electrostatic attractions and hydrogen bonding as a hybrid pillared layered framework. This hybrid sample can promote the OER in 1 M KOH with an overpotential as low as ∼410 mV (at a current density of 10 mA cm−2). In situ Raman spectroscopy showed that the sample first evolved into Co(III)-based phases comprising a mixture of layered CoOOH and spinel Co3O4, and the Co(III)-based compounds were converted into Co(IV)–O intermediates containing [CoO6] units at the onsite of the OER. The structural evolution behaviors suggest that the catalyst prefers a topotactic phase transition and the CoOh and CoTd units exhibit different activities in the electrochemical reaction. The electron transfer events involved in the electrochemical reaction were identified by Fourier-transformed alternating current voltammetry. [ABSTRACT FROM AUTHOR]

Molybdenum disulfide (MoS2), a typical two-dimensional transition metal dichalcogenide (TMD), has been widely used as an electrocatalyst for the hydrogen evolution reaction (HER). This work presented a facile electrodeposition method to fabricate binder-free Ni modified-MoS2, exhibiting superior HER catalytic performance under acidic conditions. The characterization results revealed that the as-deposited Ni–MoS2 samples have extended interlayer spacings after Ni intercalation into layered structure MoS2. The as-synthesized MoS2 with 5 at% Ni ion addition exhibits excellent electrocatalytic activity with a low onset overpotential of 139 mV. The Ni0.05Mo0.95S2 sample also exhibits the slightest Tafel slope of 62 mV dec−1, suggesting a promoted Volmer-Heyrovsky process. Besides, a low overpotential of 215 mV at 10 mA cm−2 and a high stability in H2SO4 solutions were also achieved. The excellent HER performance of the obtained material can be attributed to the synergistic effect of the formed Ni–Mo–S composition, abundant active sites and increased electrical conductivity. This work may contribute to the practical application of TMD-based electrocatalysts for hydrogen production. [ABSTRACT FROM AUTHOR]

Copper phthalocyanine on carbon (CuPc/C) after pyrolysis exhibits a C2H4 Faradaic efficiency (FEC2H4) of 42.6 ± 0.5% at an extremely low potential of −0.4 V vs. RHE toward the electrochemical CO2 reduction reaction (CO2RR), significantly boosted by the in situ oxygen reduction reaction (ORR). [ABSTRACT FROM AUTHOR]

The performance of perovskite photodetectors (PPDs) is sensitive to the quality of their perovskite films. Solution-processed perovskite films suffer from excess lead halide and irregular nanocavities located at the buried interface, which result in a high dark current density and hinder the improvement of the PPD performance. Herein, we could govern the perovskite growth by introducing the modulating MAI molecule in the PbI2 precursor in a modified two-step spin-coating method. Consequently, we obtained a high-quality (large grain size, pinhole-free and well-packed) perovskite layer with uniform thickness. Also, we fabricated a photodiode-type PPD with a p–i–n configuration. At a reverse bias of −1.5 V, the optimum PPD achieved a high specific detectivity of up to 5 × 1011 Jones and a decent responsivity of 0.79 A W−1 under 532 nm laser irradiation with a light intensity of 1 μW cm−2. Meanwhile, it exhibited a fast response of 2.6 μs and 72.8 μs for the rise and fall times, respectively. This strategy enriches the approaches for preparing high-quality perovskite films for diverse perovskite optoelectronic devices. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) perovskites have shown more considerable advantages in terms of stability than their three-dimensional (3D) counterparts. However, the intrinsic poor light absorption and charge transport capacity impede the improvement of device performance. Herein a novel 2D perovskite material containing butylammonium acetate (BAAc) is firstly introduced to fabricate high-performance and stable 2D/3D stacked perovskite photodetectors (PPDs). With the in situ growth of BAAc, the defects on the surfaces and grain boundaries of regular 3D perovskite (3D-PSK) films are dramatically passivated, and the larger size of long-chain BA+ ions not only enhances the moisture stability but also improves the thermal stability of the 2D/3D stacked perovskite films and PPDs. As a result, the responsivity of the BAAc treated PPD (BAAc-PPD) reaches 2.11 A W−1 under the illumination of a 532 nm laser, and retains 78.5% of the initial value after 20 days of nonencapsulated storage at 10–15% relative humidity (RH). In addition, we successfully demonstrate the use of our PPDs in a visible light communication system. Our work provides a simple and effective method for the fabrication of high-performance and stable 2D/3D stacked PPDs, which has great application potential in visible light communication, imaging and environmental monitoring under complex environmental conditions. [ABSTRACT FROM AUTHOR]

The preparation of most high-performance perovskite optoelectronic devices usually relies on costly inert or vacuum conditions to circumvent the inimical effects of moisture, which could lead to inferior crystallization processes and nonuniform morphology. Hence, it is imperative to develop a reliable and cost-effective approach to deposit a high-quality perovskite in ambient air. Herein, we investigated the influence of tert-butanol (TBA), sec-butanol (SBA), and isobutanol (IBA) on the nucleation mechanism in ambient atmosphere. It was found that TBA as an eco-friendly anti-solvent leads to the formation of uniform, smooth, pinhole-free, mirror-like perovskite films with enhanced optoelectronic properties compared with other solvents. More excitingly, perovskite photodetectors fabricated using TBA exhibited an excellent photoresponsivity of 1.93 A W−1, which is among the highest values reported for the same device structure and also demonstrates the distinctive advantages of our nucleation management strategy. This work sheds light on developing high-performance perovskite photodetectors using eco-friendly solutions in ambient environment. [ABSTRACT FROM AUTHOR]

Here, a sensitive sandwich-type electrochemical biosensor for microRNA-21 detection was reported. It was based on the use of a Au NP functionalized graphite-like carbon nitride nanosheet (g-C3N4 NS) nanohybrid (Au NPs–g-C3N4 NS) as a sensing platform and DNA concatemers containing methylene blue (MB) as a signal probe. The signal probe was prepared by using two different single strand DNAs with a complementary sequence (one of them labeled with MB at the 3′ end) to form long concatemers via continuous hybridization chain reaction (HCR); thus numerous MB signal molecules were loaded on long concatemers. The biosensor was fabricated following the next step: a thiolated hairpin probe (HP) was first immobilized on the surface of the glassy carbon electrode (GCE) modified with a Au NPs–g-C3N4 NS nanohybrid. After it was blocked with MCH, the modified electrode was sequentially hybridized with microRNA-21 and a signal probe, respectively. As a result, a sandwich structure of HP–microRNA–signal probe covered the surface of the modified electrode. Differential pulse voltammetry (DPV) was employed to measure the sensing signal in phosphate buffered solution (0.10 M PBS, pH 7.4). The experimental conditions were optimized such as the hybridization time and the amount of g-C3N4 NS. The proposed biosensor exhibited a wide linear response range (1.0 fM to 500 nM) and a low limit of detection (0.33 fM; at S/N = 3) under the optimal conditions. Meanwhile, the biosensor could discriminate single base mismatched microRNA-21, indicating that the biosensor possessed high selectivity. [ABSTRACT FROM AUTHOR]

Organic–inorganic halide perovskites with low thermal conductivity, high Seebeck coefficients and high carrier mobilities are promising thermoelectric materials for near infrared (NIR) and terahertz (THz) photodetectors (PDs). Here, we report a novel rapid response and self-powered NIR and THz photothermoelectric PD based on a CH3NH3PbI3 (MAPbI3) and poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) composite. An order of magnitude enhancement in the Seebeck coefficient was observed that resulted from the addition of PEDOT:PSS. Under 1064 nm and 2.52 THz illumination, the device displays a stable and repeatable photoresponse at room temperature under a zero bias voltage. The frequency response shows a −3 dB frequency band of 5 kHz, corresponding to a fast response time of 28 μs, which is approximately three orders of magnitude faster than the previously reported results. These results demonstrate that MAPbI3/PEDOT:PSS is a promising composite material for fast response and self-powered NIR-THz PTE PDs operating at room temperature. [ABSTRACT FROM AUTHOR]

We report the thermoelectric performance of p-type nanocrystalline SnSe obtained from the liquid phase sintering of blends of SnSe nanocrystals and Te nanorods. A cycled hot press procedure at a temperature above the Te melting point promoted the formation of crystallographically textured SnSe nanomaterials with relative densities up to 93%. After consolidation, part of this Te was found within the SnSe lattice and part remained as elemental Te between the SnSe grains. The presence of Te during the SnSe consolidation resulted in SnSe nanomaterials with higher electrical conductivities and lower Seebeck coefficients and thermal conductivities. By adjusting the amount of Te, thermoelectric figures of merit (ZT) up to 1.4 at 790 K were measured in the direction of the uniaxial pressure, coinciding with the preferential a crystallographic axis. While this value matches the highest ZT value reported at this temperature for SnSe in the [100] crystal direction, the ZT values of the consolidated SnSe along the bc plane were relatively lower due to moderately low thermal conductivities in this plane. [ABSTRACT FROM AUTHOR]

Dendrimers possess intriguing “dendritic effects”, which are unique characteristics that stem from the dendrimer generation and size. Here we report a “negative dendritic effect” observed during enzymatic hydrolysis of dendrimer conjugates. Such negative dendritic effects, though rarely reported, may be explored for tailored and generation-dependent drug release. [ABSTRACT FROM AUTHOR]

Nucleoside derivatives are an important class of molecules in the search for bioactive compounds. In our continuing efforts to develop novel nucleoside analogs, we used the Sonogashira cross-coupling reaction to synthesize 1,2,4-triazole acyclonucleosides bearing various arylethynyl groups on the triazole nucleobase. By employing 3-iodotriazole nucleoside as the coupling substrate, the Sonogashira reaction proceeded efficiently even with alkynes, which are notoriously unreactive and challenging. Further crystal structural analysis unveiled the coplanar feature of the 3-arylethynyltriazole motifs, suggesting their potential as surrogates for large planar aromatic systems or nucleobases. Most importantly, several synthesized compounds displayed interesting antiproliferative activity against various cancer cells and induced apoptosis, highlighting that this family of triazole nucleosides might show promise as anticancer candidates. [ABSTRACT FROM AUTHOR]

We report the synthesis of a hybrid layered cobalt hydroxide sample and its redox behaviors in the electrochemical oxygen evolution reaction (OER). Compound Co 7 (OH) 12 (C 2 H 4 S 2 O 6 )·1.6H 2 O was synthesized via a homogeneous alkalization reaction using Co(SO 3 C 2 H 4 SO 3 ) and hexamethylenetetramine. This compound comprises cationic host layers of {[Co 7 (OH) 12 ] 2+ } ∞ , which comprise octahedrally (Co Oh ) and tetrahedrally (Co Td ) coordinated Co cations at a Co Oh  : Co Td ratio of 5 : 2. The ethane-disulfonate ions are combined with the cationic host layers by electrostatic attractions and hydrogen bonding as a hybrid pillared layered framework. This hybrid sample can promote the OER in 1 M KOH with an overpotential as low as ∼410 mV (at a current density of 10 mA cm -2 ). In situ Raman spectroscopy showed that the sample first evolved into Co(III)-based phases comprising a mixture of layered CoOOH and spinel Co 3 O 4 , and the Co(III)-based compounds were converted into Co(IV)-O intermediates containing [CoO 6 ] units at the onsite of the OER. The structural evolution behaviors suggest that the catalyst prefers a topotactic phase transition and the Co Oh and Co Td units exhibit different activities in the electrochemical reaction. The electron transfer events involved in the electrochemical reaction were identified by Fourier-transformed alternating current voltammetry.

Copper phthalocyanine on carbon (CuPc/C) after pyrolysis exhibits a C 2 H 4 Faradaic efficiency (FE C 2 H 4 ) of 42.6 ± 0.5% at an extremely low potential of -0.4 V vs. RHE toward the electrochemical CO 2 reduction reaction (CO 2 RR), significantly boosted by the in situ oxygen reduction reaction (ORR).

Here, a sensitive sandwich-type electrochemical biosensor for microRNA-21 detection was reported. It was based on the use of a Au NP functionalized graphite-like carbon nitride nanosheet (g-C 3 N 4 NS) nanohybrid (Au NPs-g-C 3 N 4 NS) as a sensing platform and DNA concatemers containing methylene blue (MB) as a signal probe. The signal probe was prepared by using two different single strand DNAs with a complementary sequence (one of them labeled with MB at the 3' end) to form long concatemers via continuous hybridization chain reaction (HCR); thus numerous MB signal molecules were loaded on long concatemers. The biosensor was fabricated following the next step: a thiolated hairpin probe (HP) was first immobilized on the surface of the glassy carbon electrode (GCE) modified with a Au NPs-g-C 3 N 4 NS nanohybrid. After it was blocked with MCH, the modified electrode was sequentially hybridized with microRNA-21 and a signal probe, respectively. As a result, a sandwich structure of HP-microRNA-signal probe covered the surface of the modified electrode. Differential pulse voltammetry (DPV) was employed to measure the sensing signal in phosphate buffered solution (0.10 M PBS, pH 7.4). The experimental conditions were optimized such as the hybridization time and the amount of g-C 3 N 4 NS. The proposed biosensor exhibited a wide linear response range (1.0 fM to 500 nM) and a low limit of detection (0.33 fM; at S/N = 3) under the optimal conditions. Meanwhile, the biosensor could discriminate single base mismatched microRNA-21, indicating that the biosensor possessed high selectivity.

We here describe a fluorescent signal amplification method termed "Click-based amplification" that can be well integrated with various click-labelling modes, including chemical labelling, genetic incorporation and covalent inhibitor probe mediated target labelling. Picolyl azide (pAz) was used as a functional group of a streptavidin-based amplifier to enhance the efficiency of click chemistry. Click-based amplification provided 3.0-12.7 fold amplification on fixed HeLa cells with different click-labelling modes. Click-based amplification has proven to be superior to tyramide signal amplification (TSA) in view of its low nonspecific amplification and high signal-to-noise ratio. Moreover, in terms of the challenging signal amplification of tissue specimens, Click-based amplification successfully achieved remarkable fluorescence enhancement on intestinal tissue slices of afatinib-N 3 treated mice, which provided direct evidence of the presence of afatinib-N 3 in the intestinal tissues and helped in revealing the off-target toxicity of afatinib. Collectively, these results illustrate that Click-based amplification could serve as a promising method for bioimaging studies., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Multidrug-resistant Acinetobacter baumannii is a top-priority Gram-negative pathogen and polymyxins are a last-line therapeutic option. Previous systems pharmacological studies examining polymyxin killing and resistance usually focused on individual strains, and the derived knowledge could be limited by strain-specific genomic context. In this study, we examined the gene expression of five A. baumannii strains (34654, 1207552, 1428368, 1457504 and ATCC 19606) to determine the common differentially expressed genes in response to polymyxin treatments. A pan-genome containing 6061 genes was identified for 89 A. baumannii genomes from RefSeq database which included the five strains examined in this study; 2822 of the 6061 genes constituted the core genome. After 2 mg L -1 or 0.75 × MIC polymyxin treatments for 15 min, 41 genes were commonly up-regulated, including those involved in membrane biogenesis and homeostasis, lipoprotein and phospholipid trafficking, efflux pump and poly-N-acetylglucosamine biosynthesis; six genes were commonly down-regulated, three of which were related to fatty acid biosynthesis. Additionally, comparison of the gene expression at 15 and 60 min in ATCC 19606 revealed that polymyxin treatment resulted in a rapid change in amino acid metabolism at 15 min and perturbations on envelope biogenesis at both time points. This is the first pan-transcriptomic study for polymyxin-treated A. baumannii and our results identified that the remodelled outer membrane, up-regulated efflux pumps and down-regulated fatty acid biosynthesis might be essential for early responses to polymyxins in A. baumannii. Our findings provide important mechanistic insights into bacterial responses to polymyxin killing and may facilitate the optimisation of polymyxin therapy against this problematic 'superbug'.