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Bimetallic Au@Ag nano-sea urchins (Au@Ag NSUs) functionalized with methimazole were synthesized and combined with paper tips as efficient surface-enhanced Raman scattering (SERS) substrates for ultrasensitive Cr(VI) detection. The redox reaction between methimazole and Cr(VI) ensured the reliability of quantitative Cr(VI) analysis. When droplets were continuously dropped on the tip of the paper, based on the gravity effect, the nanoparticles achieved enrichment at the front end of the tip, which further improved the sensitivity of detection. The detection limit is as low as 0.956 ng L−1, demonstrating its excellent performance in ultrarace Cr(VI) detection. Additionally, the SERS sensor was successfully applied to the detection of Cr(VI) in real water samples, such as lake water and tap water, indicating its wide application potential in environmental monitoring. This study not only provides an efficient and reliable new method for detecting Cr(VI) but also shows the great prospect of paper-based SERS sensors in practical applications. [ABSTRACT FROM AUTHOR]

Water splitting is an energy conversion process of vital importance. The oxygen evolution reaction (OER), as the half-reaction of water splitting, has very slow kinetics due to the complex quaternary electron transfer process involved, which greatly impedes the efficiency of energy conversion. The rational construction and modification of metal–organic frameworks (MOFs) offer a novel alternative for developing efficient OER electrocatalysts. In this study, MOF-74-PA15 with abundant surface defects and high hydrophilicity was successfully in situ constructed by etching MOFs for different reaction times using phytic acid (PA). The etching of PA increases the active area, and improves the hydrophilicity, allowing tighter contact between the material and the electrolyte. As a result, MOF-74-PA15 exhibits the most optimal OER catalytic performance in all the samples. The overpotential is 250 mV in 1 M KOH at 100 mA cm−2, with the lowest Tafel slope (35.59 mV dec−1). Furthermore, MOF-74-PA15 exhibits excellent stability. It maintains stability for 72 hours at a current density of 50 mA cm−2. This study presents a novel and feasible solution for modifying MOFs as electrocatalytic water splitting catalysts. [ABSTRACT FROM AUTHOR]

To address the shortage of fossil energy, the development of affordable and efficient non-precious metal catalysts for oxygen evolution reaction (OER) from electrocatalytic water splitting is still a crucial challenge. Herein, the bimetallic NiFe metal–organic frameworks (MOFs) are synthesized by hydrothermal and electro-deposition. Benefiting from the synergistic effect of Fe and Ni, the catalyst demonstrates extraordinary activity, which exhibits favorable OER catalytic activity in 1 M KOH solution with an overpotential of 206 mV at 10 mA cm−2. Meanwhile, the obtained NiFe-NDC presents promising stability in the 20 h test at 50 mA cm−2. [ABSTRACT FROM AUTHOR]

The efficiency and reproducibility of perovskite solar cells (PSCs) are significantly influenced by the purity of lead iodide (PbI2) in the raw materials used. Pb(OH)I has been identified as the primary impurity generated from PbI2 in water-based synthesis. Consequently, a comprehensive investigation into the impact of Pb(OH)I impurities on film and device performance is essential. In this study, PbI2, with varying stoichiometries, was synthesized to examine the effects of different Pb(OH)I levels on perovskite device performance. The characterization results revealed that even trace amounts of Pb(OH)I impede the formation of precursor prenucleation clusters. These impurities also increase the energy barrier of the α-phase and facilitate the transition of the intermediate phase to the δ-phase. These effects result in poor perovskite film morphology and sub-optimal photovoltaic device performance. To address these issues, a cost-effective method for preparing high-stoichiometry PbI2 was developed. The formation of Pb(OH)I was effectively inhibited through several strategies: adjusting solution pH and temperature, modifying material addition order, simplifying the precipitation–recrystallization process, and introducing H3PO2 as an additive. These modifications enabled the one-step synthesis of high-purity PbI2. PSCs prepared using this newly synthesized high-stoichiometry PbI2 demonstrated photovoltaic performance comparable to those fabricated with commercial PbI2 (purity ≥ 99.999%). Our novel method offers a cost-effective alternative for synthesizing high-stoichiometry PbI2, thereby providing a viable option for the production of high-performance PSCs. [ABSTRACT FROM AUTHOR]

Developing efficient and economical catalysts is essential for water splitting. The application of MOF catalysts in water splitting is limited by poor conductivity; however, the introduction of conductive TMS could enhance their activity. Herein, novel composite Fe9S10/Fe-MOF/NF-2 was constructed by introducing dendritic Fe9S10 onto the surface of a 2D ultrathin Fe-MOF. Composite catalysts elaborately utilize the structural and chemical advantages of MOF and TMS while improving the deficiencies of monomers through the combination. Owing to the optimal structure, the hybrid catalyst Fe9S10/Fe-MOF/NF-2 displayed better catalytic performance than bare Fe-MOFs and Fe9S10, with low overpotentials of 202 and 216 mV at 10 mA cm−2 in alkaline solution and simulated seawater, respectively. This work provides an innovative approach to modify MOFs as electrocatalysts for OER. [ABSTRACT FROM AUTHOR]

The use of photocatalysts based on semiconductor heterostructures for hydrogen evolution is a prospective tactic for converting solar energy. Herein, visible-light-responsive three-dimensional core–shell CoSe2/ZnIn2S4 heterostructures were successfully fabricated via in situ growth of ZnIn2S4 ultrathin nanosheets on spherical CoSe2. Without any noble metal co-catalysts, the as-prepared CoSe2/ZnIn2S4 composite achieved attractive photocatalytic hydrogen evolution activity under visible light illumination. Optimal CoSe2/ZnIn2S4 achieved a hydrogen evolution rate of 2199 μmol g−1 h−1, which was 7 times higher than that of pristine ZnIn2S4 and even exceeded that of ZnIn2S4 loaded with platinum. In this distinctive core–shell heterostructure, the presence of CoSe2 could considerably improve the ability to harvest light, quicken the charge transfer kinetics, and avoid the agglomeration of ZnIn2S4 nanosheets. Meanwhile, the experimental results demonstrated that the strong interaction between CoSe2 and ZnIn2S4 at the compact interface could appropriately boost the photogenerated electron–hole pair migration and relieve charge recombination, thus improving photocatalytic hydrogen evolution activity. This work has bright prospects in constructing noble-metal-free core–shell heterostructures for solar energy conversion. [ABSTRACT FROM AUTHOR]

Chemical mechanism (CM)-related surface-enhanced Raman spectroscopy (SERS) has received tremendous interest due to its exceptional stability and excellent uniformity. Nevertheless, there remains a demand for ingenious methodologies for promoting effective charge transfer (CT) to improve SERS sensitivity further. Herein, a band structure engineered W18O49/g-C3N4 heterostructure (WCN) was first employed as a CM-based SERS substrate with remarkable enhancement and sensitivity. To investigate the Raman enhancement properties of the substrate, malachite green (MG) was employed as the Raman probe with the excitation of a 633 nm laser. The WCN substrate exhibits a Raman enhancement factor (EF) of 2.6 × 107, achieving a limit of detection (LOD) of 1.9 × 10−10 M for MG. The outstanding Raman amplification behavior can be attributed to the heterojunction-induced efficient CT process, energy band matching resonance due to minor doping with g-C3N4 serving as a band gap modifier, and improved photo-induced charge transfer (PICT) efficiency via the oxygen vacancies in the W18O49 units. Additionally, a flexible SERS substrate based on WCN was constructed using a vacuum filtration method and utilized to detect prohibited pharmaceutical residues on fish skin. The integration of this WCN and a nylon membrane not only preserves the Raman activity of the WCN for sensitive detection but also endows the Raman substrate with high flexibility and good mechanical durability, making it a potential candidate for in situ detection in particular environments. [ABSTRACT FROM AUTHOR]

High-performance SERS chips via self-assembled hollow Ag octahedra on PDMS were employed to achieve the sensitive identification and detection of antibiotic residues. The developed SERS chips were successfully applied in the detection of ciprofloxacin (CIP), amoxicillin (AMX) and cefazolin (CZL) in wastewater and tap water samples, as well as enrofloxacin (ENR) in milk, demonstrating the sensitive determination of antibiotics in the real environment. From this perspective, these SERS chips are expected to expand the on spot sensitive detection and identification field of antibiotic residues. [ABSTRACT FROM AUTHOR]

It is widely acknowledged that interface engineering strategies can significantly enhance the activity of catalysts. In this study, we developed a CoMoP nanoarray directly grown in situ on a nickel foam (NF) substrate, with the interface structure formed through the electrodeposition of MnOxHy. The resulting heterostructure MnOxHy/CoMoP/NF exhibited remarkable hydrogen evolution reaction (HER) activity, achieving overpotentials as low as 61 and 138 mV at 10 and 100 mA cm−2, respectively. Moreover, MnOxHy/CoMoP/NF demonstrated efficient oxygen evolution reaction (OER) activity with an overpotential of 330 mV at 100 mA cm−2. Remarkably, MnOxHy/CoMoP/NF maintained its catalytic properties and structural integrity even after working continuously for 20 h facilitating the HER at 10 mA cm−2 and the OER at 100 mA cm−2. The Tafel slopes of the HER and OER were determined to be as small as 14 and 55 mV dec−1, respectively, confirming that the coupled interface conferred fast reaction kinetics on the catalyst. When applied in overall water splitting, MnOxHy/CoMoP/NF delivered a voltage of 1.91 V at 100 mA cm−2 with excellent stability. This study demonstrated the feasibility of utilizing a simple electrodeposition technique to fabricate a heterogeneous structure with bifunctional catalytic activity, establishing a solid foundation for diverse industrial applications. [ABSTRACT FROM AUTHOR]

The design of an efficient OER catalyst is significant for water splitting. Metal–organic frameworks (MOFs) are emerging as promising electrocatalysts due to their diversity of structure and tunability of function. In this paper, 2D FexCo1−x-MOF1/NF with an extended ligand (biphenyl-4,4′-dicarboxylic acid, BPDC) is constructed on nickel foam by a solvothermal method. Compared with the MOF2 synthesized by using BDC (1,4-bezenedicarboxylate), MOF1 shows excellent performance. Among MOF1, Fe0.5Co0.5-MOF1/NF exhibits outstanding performance with a low overpotential (217 mV) and a small Tafel slope (31.16 mV Dec−1) at 10 mA cm−2 and performs well at a high current density. In addition, the catalyst is remarkable in terms of durability both in alkaline solution and simulated seawater. The synergetic effect between Fe and Co and more active sites exposed play an important role in improving the OER activity. This work provides an effective strategy for the rational design of MOFs as inexpensive electrocatalysts. [ABSTRACT FROM AUTHOR]

Solar-driven water splitting offers a leading-edge approach to storing abundant and intermittent solar energy and producing hydrogen as a clean and sustainable energy carrier. More importantly, constructing well-designed photocatalysts is a promising approach to develop clean hydrogen energy. In this paper, flower spherical UiO-66-(SCH3)2/ZnIn2S4 (UiOSC/ZIS) photocatalysts are successfully synthesized by a simple two-step hydrothermal method, and they exhibit high hydrogen production activity in light-driven water splitting. The optimized 30-UiOSC/ZIS (the content of UiOSC was 30 mg) composite exhibits optimal hydrogen production activity with a hydrogen production of 3433 μmol g−1 h−1, which is 5 and 235 times higher than that of pure ZIS and UiOSC, respectively. In addition, a long-cycling stability test has shown that the UiOSC/ZIS composite has good stability and recyclability. Experimental and characterization results show the formation of a type-II heterojunction between UiOSC and ZIS. This effectively suppresses the recombination of electrons–holes and promotes the carrier transfer, thus significantly improving the hydrogen production performance. This research further promotes the application of UiO-66-(SCH3)2 in the field of photocatalytic hydrogen production and provides a reference for the rational design of UiO-66-based composite photocatalysts. [ABSTRACT FROM AUTHOR]

Electrochemical water splitting is a potential green hydrogen energy generation technique. With the shortage of fresh water, abundant seawater resources should be developed as the main raw material for water electrolysis. However, since the precipitation reaction of chloride ions in seawater will compete with the oxygen evolution reaction (OER) and corrode the catalyst, seawater electrolysis is restricted by the decrease in activity, low stability, and selectivity. Rational design and development of efficient and stable catalysts is the key to seawater electrolysis. Herein, a high-activity bimetallic phosphide FeCoP, grown on a reduced graphene oxide (rGO)-protected Ni Foam (NF) substrate using FeCo Prussian Blue Analogue (PBA) as a template, was designed for application in alkaline natural seawater electrolysis. The OER activity confirmed that the formed FeCoP@rGO/NF has high electrocatalytic performance. In 1 M KOH and natural alkaline seawater, the overpotential was only 257 mV and 282 mV under 200 mA cm−2, respectively. It also demonstrated long-term stability up to 200 h. Therefore, this study provides new insight into the application of PBA as a precursor of bimetallic phosphide in the electrolysis of seawater at high current density. [ABSTRACT FROM AUTHOR]

Metal halide perovskites represented by methylamine lead iodine (MAPbI3) have attracted extensive attention for their excellent performance in the field of photoelectric catalysis. However, the catalytic performance of MAPbI3 is limited due to the severe recombination of electrons and holes. Here, we synthesized hollow MoS2 (H-MoS2) microspheres by the template method and then supported it on the surface of MAPbI3 by electrostatic coupling to obtain H-MoS2/MAPbI3 composites, which showed excellent performance in photocatalytic hydrogen production. Among them, the 15% H-MoS2/MAPbI3 composite showed the highest photocatalytic hydrogen evolution performance, which was 399 μmol h−1, about 260 times that of MAPbI3 (1.53 μmol h−1). The long-term cycling experiments showed that the H-MoS2/MAPbI3 composite retains its activity for at least 16 h. The excellent performance of H-MoS2/MAPbI3 composites was attributed to the efficient shunting of photogenerated electrons and holes by H-MoS2 as a cocatalyst. The results of our study provided a reference for the construction of MAPbI3-based composite heterostructures for efficient photocatalytic hydrogen production. [ABSTRACT FROM AUTHOR]

Developing high-performance catalysts is an effective strategy for speeding up the oxygen evolution reaction (OER) and increasing production efficiency. Here, a core–shell electrocatalyst consisting of CoMoO4 nanorods grown in situ on nickel foam substrate covered by nickel–iron layered double hydroxide (NiFe-LDH) via electrodeposition was demonstrated (CoMoO4/NiFe-LDH@NF). Experimental investigations revealed that self-supporting and binder-free electrodes ensured that the catalysts exposed an abundance of active sites, faster electron transfer, and excellent long-cycle stability. The NiFe-LDH shell with a crystalline-amorphous dual structure served as an accurate active material, lowering the energy barrier and contributing more catalytic sites for water oxidation. Furthermore, the core CoMoO4 nanorods not only effectively avoided the accumulation of NiFe-LDH to increase the electrochemically active area but also acted as a highway for electrons from the active site to the substrate to promote the OER kinetics. Specifically, CoMoO4/NiFe-LDH@NF exhibited lower overpotential (180 mV at 10 mA cm−2) and smaller Tafel slope (34 mV dec−1) than pure CoMoO4@NF and NiFe-LDH@NF, revealing its excellent catalytic performance and fast intrinsic reaction kinetics. In addition, CoMoO4/NiFe-LDH@NF exhibited long-term stability of more than 20 h at 50 mA cm−2, further demonstrating its potential for practical applications. These findings pointed to a potential option for building innovative OER catalysts. [ABSTRACT FROM AUTHOR]

The UiO-66 family shows promising photocatalytic prospects in water splitting for hydrogen evolution under visible light irradiation due to its suitable band gap and adequate active sites. In this work, novel Ni2P/UiO-66-(SCH3)2 composites were prepared by a simple solvothermal method. These as-synthesized samples were fully characterized by XRD, SEM, TEM, HRTEM, EDS, and XPS methods. The effectiveness of visible light driven photocatalytic water-splitting to produce hydrogen was investigated in the presence of sacrificial agents. The results showed that the optimal hydrogen yield of 5 wt% Ni2P/UiO-66-(SCH3)2 is 3724.22 μmol g−1 h−1, reaching almost 187 times that of pristine UiO-66-(SCH3)2 (19.93 μmol g−1 h−1). Meanwhile, long term cycling stability tests also showed that Ni2P/UiO-66-(SCH3)2 composites present an excellent photocatalytic H2 production stability. Photoelectrochemical performance analysis revealed that the high catalytic activity of the composite materials could be associated with the synergistic effect of UiO-66-(SCH3)2 and Ni2P. Light stimulates UiO-66-(SCH3)2 to generate electrons and holes, and Ni2P as a cocatalyst could effectively transmit electrons and boost photogenerated charge separation. This work provides a reference for exploring UiO-66 family catalysts with good catalytic activity. [ABSTRACT FROM AUTHOR]

All‐inorganic metal halide perovskite quantum dots (QDs) have attracted attention from researchers with their fascinating optoelectronic properties. However, blue‐emitting perovskite QDs typically have low photoluminescence quantum yield (PLQY). For potential commercial applications, it is preferable to replace Pb with an element having low toxicity. Here, Pb‐free Cs3Bi2Br9@BiOBr perovskite QDs were anchored on the surface of NHx‐rich monodisperse silica (A−SiO2) via N−Bi chemical bonding to isolate QDs from each other, thus enhancing efficient surface passivation and suppressing optical decay. Compared to unanchored QDs, Cs3Bi2Br9@BiOBr QDs/A−SiO2 composites exhibited significantly enhanced blue emission performance, the PLQY of which increased from 16.62 % to 77.26 %, in addition to good water and environmental stability. Finally, the novel composites as photocatalysts were used to drive the oxidation of toluene, a template reaction of C(sp3)−H bond activation and demonstrated astonishing conversion rates (4317 μmol g−1 h−1) with high selectivity (around 87 %). [ABSTRACT FROM AUTHOR]