Phase‐Regulated Sensing Mechanism of MoS2 Based Nanohybrids toward Point‐of‐Care Prostate Cancer Diagnosis

Alpha‐methylacyl‐CoA racemase (AMACR) has been proven to be consistently overexpressed in prostate cancer epitheliums, and is expected to act as a positive biomarker for the diagnosis of prostate carcinoma in clinical practice. Here, a strategy for specific determination of AMACR in real human serum by using an electrochemical microsensor system is presented. In order to implement the protocol, a self‐organized nanohybrid consisting of metal nanopillars in a 2D MoS₂ matrix is developed as material for the sensing interface. The testing signal outputs are strongly enhanced with the presence of the nanohybrids owing to that the metal pillars provide an efficient mass difussion and electron transfer path to the MoS₂ film surface. Furthermore, the phase‐regulated sensing mechanism over MoS₂ is noticed and demonstrated by density functional theory calculation and experiments. The explored MoS₂ based nanohybrids are employed for the fabrication of an electrochemical microsensor, presenting good linear relationship in both ng µL^?1 and pg µL^?1 ranges for AMACR quantification. The sampling analysis of human serum indicates that this microsensor has good diagnostic specificity and sensitivity toward AMACR. The proposed electrochemical microsensor system also demonstrates the advantages of convenience, cost‐effectiveness, and disposability, resulting in a potential integrated microsystem for point‐of‐care prostate cancer diagnosis.     

Photocatalytic Conversion of CO2 into Renewable Hydrocarbon Fuels: State‐of‐the‐Art Accomplishment,Challenges, and Prospects

Photocatalytic reduction of CO₂ into hydrocarbon fuels, an artificial photosynthesis, is based on the simulation of natural photosynthesis in green plants, whereby O₂ and carbohydrates are produced from H₂O and CO₂ using sunlight as an energy source. It couples the reductive half‐reaction of CO₂ fixation with a matched oxidative half‐reaction such as water oxidation, to achieve a carbon neutral cycle, which is like killing two birds with one stone in terms of saving the environment and supplying future energy. The present review provides an overview and highlights recent state‐of‐the‐art accomplishments of overcoming the drawback of low photoconversion efficiency and selectivity through the design of highly active photocatalysts from the point of adsorption of reactants, charge separation and transport, light harvesting, and CO₂ activation. It specifically includes: i) band‐structure engineering, ii) nanostructuralization, iii) surface oxygen vacancy engineering, iv) macro‐/meso‐/microporous structuralization, v) exposed facet engineering, vi) co‐catalysts, vii) the development of a Z‐scheme system. The challenges and prospects for future development of this field are also present.     

Fe2O3–TiO2 Nano‐heterostructure Photoanodes for Highly Efficient Solar Water Oxidation

Harnessing solar energy for the production of clean hydrogen by photo­electrochemical water splitting represents a very attractive, but challenging approach for sustainable energy generation. In this regard, the fabrication of Fe₂O₃–TiO₂ photoanodes is reported, showing attractive performances [≈2.0 mA cm⁻² at 1.23 V vs. the reversible hydrogen electrode in 1 M NaOH] under simulated one‐sun illumination. This goal, corresponding to a tenfold photoactivity enhancement with respect to bare Fe₂O₃, is achieved by atomic layer deposition of TiO₂ over hematite (α‐Fe₂O₃) nanostructures fabricated by plasma enhanced‐chemical vapor deposition and final annealing at 650 °C. The adopted approach enables an intimate Fe₂O₃–TiO₂ coupling, resulting in an electronic interplay at the Fe₂O₃/TiO₂ interface. The reasons for the photocurrent enhancement determined by TiO₂ overlayers with increasing thickness are unraveled by a detailed chemico‐physical investigation, as well as by the study of photo­generated charge carrier dynamics. Transient absorption spectroscopy shows that the increased photoelectrochemical response of heterostructured photoanodes compared to bare hematite is due to an enhanced separation of photogenerated charge carriers and more favorable hole dynamics for water oxidation. The stable responses obtained even in simulated seawater provides a feasible route in view of the eventual large‐scale generation of renewable energy.     

Solvent‐Free Synthesis of Uniform MOF Shell‐Derived Carbon Confined SnO2/Co Nanocubes for Highly Reversible Lithium Storage

Tin dioxide (SnO₂) has attracted much attention in lithium‐ion batteries (LIBs) due to its abundant source, low cost, and high theoretical capacity. However, the large volume variation, irreversible conversion reaction limit its further practical application in next‐generation LIBs. Here, a novel solvent‐free approach to construct uniform metal–organic framework (MOF) shell‐derived carbon confined SnO₂/Co (SnO₂/Co@C) nanocubes via a two‐step heat treatment is developed. In particular, MOF‐coated CoSnO₃ hollow nanocubes are for the first time synthesized as the intermediate product by an extremely simple thermal solid‐phase reaction, which is further developed as a general strategy to successfully obtain other uniform MOF‐coated metal oxides. The as‐synthesized SnO₂/Co@C nanocubes, when tested as LIB anodes, exhibit a highly reversible discharge capacity of 800 mAh g^?1 after 100 cycles at 200 mA g^?1 and excellent cycling stability with a retained capacity of 400 mAh g^?1 after 1800 cycles at 5 A g^?1. The experimental analyses demonstrate that these excellent performances are mainly ascribed to the delicate structure and a synergistic effect between Co and SnO₂. This facile synthetic approach will greatly contribute to the development of functional metal oxide‐based and MOF‐assisted nanostructures in many frontier applications.     

Noble Metal‐Free Nanocatalysts with Vacancies for Electrochemical Water Splitting

The fast development of nanoscience and nanotechnology has significantly advanced the fabrication of nanocatalysts and the in‐depth study of the structural‐activity characteristics of materials at the atomic level. Vacancies, as typical atomic defects or imperfections that widely exist in solid materials, are demonstrated to effectively modulate the physicochemical, electronic, and catalytic properties of nanomaterials, which is a key concept and hot research topic in nanochemistry and nanocatalysis. The recent experimental and theoretical progresses achieved in the preparation and application of vacancy‐rich nanocatalysts for electrochemical water splitting are explored. Engineering of vacancies has shown to open up a new avenue beyond the traditional morphology, size, and composition modifications for the development of nonprecious electrocatalysts toward efficient energy conversion. First, an introduction followed by discussions of different types of vacancies, the approaches to create vacancies, and the advanced techniques widely used to characterize these vacancies are presented. Importantly, the correlations between the vacancies and activities of the vacancy‐rich electrocatalysts via tuning the electronic states, active sites, and kinetic energy barriers are reviewed. Finally, perspectives on the existing challenges along with some opportunities for the further development of vacancy‐rich noble metal‐free electrocatalysts with high performance are discussed.     

Automated Fabrication of 2‐nm Solid‐State Nanopores for Nucleic Acid Analysis

We demonstrate the automated and reproducible fabrication of sub‐2‐nm nanopores in 10‐nm thick silicon nitride membranes, through controlled dielectric breakdown in solution. Our results reveal that under the appropriate conditions, nanopores can be fabricated with a size no larger than 2.0 ± 0.5‐nm in diameter for a sample of N = 23 nanopores, with an average and standard deviation of 1.3 ± 0.6‐nm. The dimensions of these nanopores are confirmed by using individual translocating DNA molecules as molecular rulers. We show that a 2.0‐nm and a 2.1‐nm diameter nanopore are capable of distinguishing single‐stranded DNA versus double‐stranded DNA, and that a 2.4‐nm diameter nanopore can be used to investigate the overstretching transition in short dsDNA fragments. These results highlight the reliability and precision of the automated fabrication of nanopores via controlled dielectric breakdown, showing great promise for the manufacturing of future nanopore‐based technologies.     

Large‐Pore Mesoporous CeO2–ZrO2 Solid Solutions with In‐Pore Confined Pt Nanoparticles for Enhanced CO Oxidation

Active and stable catalysts are highly desired for converting harmful substances (e.g., CO, NO_x) in exhaust gases of vehicles into safe gases at low exhaust temperatures. Here, a solvent evaporation–induced co‐assembly process is employed to design ordered mesoporous Ce_xZr_1?xO₂ (0 ≤ x ≤ 1) solid solutions by using high‐molecular‐weight poly(ethylene oxide)‐block‐polystyrene as the template. The obtained mesoporous Ce_xZr_1?xO₂ possesses high surface area (60–100 m² g^?1) and large pore size (12–15 nm), enabling its great capacity in stably immobilizing Pt nanoparticles (4.0 nm) without blocking pore channels. The obtained mesoporous Pt/Ce_0.8Zr_0.2O₂ catalyst exhibits superior CO oxidation activity with a very low T₁₀₀ value of 130 °C (temperature of 100% CO conversion) and excellent stability due to the rich lattice oxygen vacancies in the Ce_0.8Zr_0.2O₂ framework. The simulated catalytic evaluations of CO oxidation combined with various characterizations reveal that the intrinsic high surface oxygen mobility and well‐interconnected pore structure of the mesoporous Pt/Ce_0.8Zr_0.2O₂ catalyst are responsible for the remarkable catalytic efficiency. Additionally, compared with mesoporous Pt/Ce_xZr_1?xO₂‐s with small pore size (3.8 nm), ordered mesoporous Pt/Ce_xZr_1?xO₂ not only facilitates the mass diffusion of reactants and products, but also provides abundant anchoring sites for Pt nanoparticles and numerous exposed catalytically active interfaces for efficient heterogeneous catalysis.     

2D Porous TiO2 Single‐Crystalline Nanostructure Demonstrating High Photo‐Electrochemical Water Splitting Performance

Porous single crystals are promising candidates for solar fuel production owing to their long range charge diffusion length, structural coherence, and sufficient reactive sites. Here, a simple template‐free method of growing a selectively branched, 2D anatase TiO₂ porous single crystalline nanostructure (PSN) on fluorine‐doped tin oxide substrate is demonstrated. An innovative ion exchange–induced pore‐forming process is designed to successfully create high porosity in the single‐crystalline nanostructure with retention of excellent charge mobility and no detriment to crystal structure. PSN TiO₂ film delivers a photocurrent of 1.02 mA cm^?2 at a very low potential of 0.4 V versus reversible hydrogen electrode (RHE) for photo‐electrochemical water splitting, closing to the theoretical value of TiO₂ (1.12 mA cm^?2). Moreover, the current–potential curve featuring a small potential window from 0.1 to 0.4 V versus RHE under one‐sun illumination has a near‐ideal shape predicted by the Gartner Model, revealing that the charge separation and surface reaction on the PSN TiO₂ photoanode are very efficient. The photo‐electrochemical water splitting performance of the films indicates that the ion exchange–assisted synthesis strategy is effective in creating large surface area and single‐crystalline porous photoelectrodes for efficient solar energy conversion.     

Sb‐Doped SnO2 Nanorods Underlayer Effect to the α‐Fe2O3 Nanorods Sheathed with TiO2 for Enhanced Photoelectrochemical Water Splitting

Here, a Sb‐doped SnO₂ (ATO) nanorod underneath an α‐Fe₂O₃ nanorod sheathed with TiO₂ for photoelectrochemical (PEC) water splitting is reported. The experimental results, corroborated with theoretical analysis, demonstrate that the ATO nanorod underlayer effect on the α‐Fe₂O₃ nanorod sheathed with TiO₂ enhances the PEC water splitting performance. The growth of the well‐defined ATO nanorods is reported as a conductive underlayer to improve α‐Fe₂O₃ PEC water oxidation performance. The α‐Fe₂O₃ nanorods grown on the ATO nanorods exhibit improved performance for PEC water oxidation compared to α‐Fe₂O₃ grown on flat fluorine‐doped tin oxide glass. Furthermore, a simple and facile TiCl₄ chemical treatment further introduces TiO₂ passivation layer formation on the α‐Fe₂O₃ to reduce surface recombination. As a result, these unique nanostructures show dramatically improved photocurrent density (139% higher than that of the pure hematite nanorods).     

MOF‐Confined Sub‐2 nm Atomically Ordered Intermetallic PdZn Nanoparticles as High‐Performance Catalysts for Selective Hydrogenation of Acetylene

Controllable synthesis of ultrasmall atomically ordered intermetallic nanoparticles is a challenging task, owing to the high temperature commonly required for the formation of intermetallic phases. Here, a metal–organic framework (MOF)‐confined co‐reduction strategy is developed for the preparation of sub‐2 nm intermetallic PdZn nanoparticles, by employing the well‐defined porous structures of calcinated ZIF‐8 (ZIF‐8C) and an in situ co‐reduction therein. HAADF‐STEM, HRTEM, and EDS characterizations reveal the homogeneous dispersion of these sub‐2 nm intermetallic PdZn nanoparticles within the ZIF‐8C frameworks. XRD, XPS, and EXAFS measurements further confirm the atomically ordered intermetallic phase nature of these sub‐2 nm PdZn nanoparticles. Selective hydrogenation of acetylene evaluation results show the excellent catalytic properties of the sub‐2 nm intermetallic PdZn, which result from the energetically more favorable path for acetylene hydrogenation and ethylene desorption over the ultrasmall particles than over larger‐sized intermetallic PdZn as revealed by density functional theory (DFT) calculations. Moreover, this protocol is also extendable for the preparation of sub‐2 nm intermetallic PtZn nanoparticles and is expected to provide a novel methodology in synthesizing ultrasmall atomically ordered intermetallic nanomaterials by rationally functionalizing MOFs.     

Multilayer Amorphous‐Si‐B‐C‐N/γ‐Al2O3/α‐Al2O3 Membranes for Hydrogen Purification

The hydrogen and carbon monoxide separation is an important step in the hydrogen production process. If H₂ can be selectively removed from the product side during hydrogen production in membrane reactors, then it would be possible to achieve complete CO conversion in a single‐step under high temperature conditions. In the present work, the multilayer amorphous‐Si‐B‐C‐N/γ‐Al₂O₃/α‐Al₂O₃ membranes with gradient porosity have been realized and assessed with respect to the thermal stability, geometry of pore space and H₂/CO permeance. The α‐Al₂O₃ support has a bimodal pore‐size distribution of about 0.64 and 0.045 µm being macroporous and the intermediate γ‐Al₂O₃ layer—deposited from boehmite colloidal dispersion—has an average pore‐size of 8 nm being mesoporous. The results obtained by the N₂‐adsorption method indicate a decrease in the volume of micropores—0.35 vs. 0.75 cm³ g^?1—and a smaller pore size ?6.8 vs. 7.4 Å—in membranes with the intermediate mesoporous γ‐Al₂O₃ layer if compared to those without. The three times Si‐B‐C‐N coated multilayer membranes show higher H₂/CO permselectivities of about 10.5 and the H₂ permeance of about 1.05 × 10^?8 mol m^?2 s^?1 Pa^?1. If compared to the state of the art of microporous membranes, the multilayer Si‐B‐C‐N/γ‐Al₂O₃/α‐Al₂O₃ membranes are appeared to be interesting candidates for hydrogen separation because of their tunable nature and high‐temperature and high‐pressure stability.     

Electronic and Structural Engineering of Carbon‐Based Metal‐Free Electrocatalysts for Water Splitting

Since first being reported as possible electrocatalysts to substitute platinum for the oxygen reduction reaction (ORR), carbon‐based metal‐free nanomaterials have been considered a class of promising low‐cost materials for clean and sustainable energy‐conversion reactions. However, beyond the ORR, the development of carbon‐based catalysts for other electrocatalytic reactions is still limited. More importantly, the intrinsic activity of most carbon‐based metal‐free catalysts is inadequate compared to their metal‐based counterparts. To address this challenge, more design strategies are needed in order to improve the overall performance of carbon‐based materials. Herein, using water splitting as an example, some state‐of‐the‐art strategies in promoting carbon‐based nanomaterials are summarized, including graphene, carbon nanotubes, and graphitic‐carbon nitride, as highly active electrocatalysts for hydrogen evolution and oxygen evolution reactions. It is shown that by rationally tuning the electronic and/or physical structure of the carbon nanomaterials, adsorption of reaction intermediates is optimized, consequently improving the apparent electrocatalytic performance. These strategies may facilitate the development in this area and lead to the discovery of advanced carbon‐based nanomaterials for various applications in energy‐conversion processes.