Porous Nanosheet Structure Research Articles

General synthesis of porous metal oxides nanosheets for gas sensing by gradient crystallization induced spatial confinement approach

Inorganic-template synthesis of crystalline porous metal oxides nanosheets with fantastic properties is a powerful approach, but it is limited in the systems with strong interaction between inorganic crystals and guest species. Here, we report a gradient crystallization induced spatial confinement method to achieve a general synthesis of porous metal oxides nanosheets regardless of host–guest interaction. Taking the synthesis of porous SnO2 nanosheets as an example, the freezing of KCl/SnCl2 aqueous solution induces the gradient crystallization of lamellar ice and KCl structure, and subsequently expelled KCl/SnCl2 crystals can be limited in the confined region to form the ice/SnCl2/KCl sandwich structure. Followed by freeze-drying, calcination and water washing, the porous SnO2 nanosheets structure can be obtained. Notably, this general method enables the synthesis of functional porous nanosheet with specific designed component and surface properties, and the obtained porous Pt-SnO2 nanosheets with abundant accessible active sites and lower d-band center exhibit superior gas sensing performance to 3-hydroxy-2-butanone.

Photocatalytic reduction of the uranium(Ⅵ) by ultra-thin porous g-C3N4 nanosheets synthesized via microwave-assisted

Graphitic carbon nitride (g-C3N4) has garnered significant attention in the realm of photocatalytic reduction of U(Ⅵ) from aqueous solutions owing to its favorable bandgap and visible light responsiveness. Nevertheless, conventionally prepared bulk g-C3N4 suffers from limitations such as a small specific surface area and high recombination of photo-generated charges, consequently impeding the efficiency of photocatalytic reactions and hampering practical applications. To address these shortcomings, this study presents a novel approach wherein ultra-thin porous g-C3N4 nanosheets were successfully synthesized through the microwave-assisted calcination of urea in a single step. The resulting g-C3N4 nanosheets exhibit a multi-hollow mesh structure with a significantly enlarged specific surface area, the specific surface area and pore size of MCN90 are 170 m²/g and 17 nm, respectively, which are 2.3 times and 8 times that of the bulk g-C3N4. Photocatalytic experiments revealed that these ultra-thin porous nanosheets demonstrate superior performance in the reduction of U(Ⅵ) to U(Ⅳ), achieving a reduction rate of 100 % within 20 minutes for the optimal sample, as opposed to 78 % in 40 minutes for bulk g-C3N4. This enhanced photocatalytic activity can be primarily attributed to the unique ultra-thin porous nanosheet structure, which facilitates increased specific surface areas, improve photoelectric properties, and substantially shortened electron migration distances which reduce the recombination efficiency of photogenerated electrons and holes pairs. Consequently, these findings not only offer insights into the optimization of g-C3N4 for U(Ⅵ) reduction but also provide a valuable reference for the preparation of other two-dimensional ultra-thin porous materials aimed at similar applications.

Pyrenetetrasulfonate-grafted 2D ultrathin metal–organic layer as new electrochemiluminescence emitters for ultrasensitive microRNA-21 assay

The exploration of novel electrochemiluminescence (ECL) luminophores with excellent ECL properties is a current research hotspot in the ECL field. Herein, a novel high-efficiency Ru-complex-free ECL emitter PyTS-Zr-BTB-MOL has been prepared by using porous ultrathin Zr-BTB metal–organic layer (MOL) as carrier to coordinatively graft the cheap and easily available polycyclic aromatic hydrocarbon (PAH) derivative luminophore PyTS whose ECL performance has never been investigated. Gratifyingly, the ECL intensity and efficiency of PyTS-Zr-BTB-MOL were markedly enhanced compared to both PyTS monomers and PyTS aggregates. The main reason was that the distance between pyrene rings was greatly expanded after the PyTS grafting on the Zr6 clusters of Zr-BTB-MOL, which overcame the aggregation-caused quenching (ACQ) effect of PyTS and thus enhanced the ECL emission. Meanwhile, the porous nanosheet structure of PyTS-Zr-BTB-MOL could distinctly increase the exposure of PyTS luminophores and shorten the diffusion paths of coreactants and electrons/ions, which effectively promoted the electrochemical excitation of more PyTS luminophores and thus achieved a further ECL enhancement. In light of the remarkable ECL property of PyTS-Zr-BTB-MOL, it was employed as an ECL indicator to build a novel high-sensitivity ECL biosensor for microRNA-21 determination, possessing a satisfactory response range (100 aM to 100 pM) and an ultralow detection limit (10.4 aM). Overall, this work demonstrated that using MOLs to coordinatively graft the PAH derivative luminophores to eliminate the ACQ effect and increase the utilization rate of the luminophores is a promising and efficient strategy to develop high-performance Ru-complex-free ECL materials for assembling ultrasensitive ECL biosensing platforms.

Bi2O3@reduced graphene oxide and NiCo2@Ni3Co electrodes for all-electrodeposited high-performance supercapacitors

A novel α-Bi2O3@reduced graphene oxide (rGO) composite negative electrode is designed using an electrodeposition technique, exhibiting an activation process during the first 100 charge-discharge cycles. The bismuth compounds in an initial adsorbed state gradually transformed into a dissolved state, resulting in a distinctive morphological change and the formation of a porous nanosheet structure. At a current density of 1 A/g, the α-Bi2O3@rGO achieves a specific capacitance of 1144 F/g (317 mAh/g), representing 92.18 % of its theoretical value. Even when the current density is increased by 20 times, the capacitance still maintains at 91.71 %. Additionally, a multi-layered composite cathode of NiCo2@Ni3Co is prepared. Based on these two electrodes, an all-electrodeposited soft-packaged supercapacitor (AESPS) is assembled, reaching an energy density of 107.8 Wh/kg at a power density of 800 W/kg, and 73.8 Wh/kg at 16 kW/kg. These outstanding electrochemical performances strongly demonstrate their potential in novel energy storage devices.

Iron carbide anchored on N-doped hierarchically porous carbon core/shell architecture for highly efficient OER water splitting

Metal-nitrogen-carbon complexes are emerging as efficient electrocatalysts for the oxygen evolution reaction (OER) owing to the excellent activity, stability, natural abundance, and cost-effectiveness of these complexes. This study introduces an innovative approach to synthesizing an N-doped porous graphitic carbon with a Fe3C core-shell structure (N-PGC@Fe3C) using biomass-derived carbon. Characterized by a large specific surface area of 3169 m2/g and hierarchical mesoporosity, the synthesized N-PGC@Fe3C catalysts demonstrate superior OER activity, achieving low overpotentials of 143.8 and 312.2 mV at current densities of 20 and 50 mA/cm2, respectively, in a 1 M KOH electrolyte. Notably, the N-PGC@Fe3C-3 exhibits outstanding cycle performance after 2000 cycles. Density functional theory calculations confirm that the core-shell-structured N-PGC@Fe3C provides the primary active site for the OER. The observed efficiency is attributed to the synergistic action of the Fe–N–C active sites, ultrafine Fe3C encapsulation, and the hierarchical porous nanosheet structure that facilitates mass diffusion and increases the exposure of active sites. Furthermore, when employed as an anode during overall water splitting, N-PGC@Fe3C achieves a cell voltage of 1.49 V at a current density of 10 mA/cm2 under alkaline conditions. This study can facilitate the development of high-performance Fe–N–C-based catalysts and clarify the underlying OER mechanisms, thereby advancing the field of electrocatalytic water splitting and energy storage systems.

Integrated Heterogeneous Engineering with the Vacancy Defect of Porous CoPv-MoxPv Nanosheets for an Accelerated Hydrogen Evolution Reaction.

Electrochemical water splitting is a possible way of realizing sustainable and clean hydrogen production but is challenging, because a highly active and durable electrocatalyst is essential. In this work, we integrated heterogeneous engineering and vacancy defect strategies to design and fabricate a heterostructure electrocatalyst (CoPv-MoxPv/CNT) with abundant phosphorus vacancies attached to carbon nanotubes (CNTs). The vacancy defects enabled the optimization of the electronic structure; thereby, the electron-rich low-valent metal sites enhanced the ability of nonmetallic P to capture proton H. Meanwhile, the heterogeneous interface between bimetallic phosphides and CNTs realized rapid electron transfer. In addition, the Co, Mo, and P active species in the electrocatalytic process exposed increased amounts of active sites featuring porous nanosheet structures, which facilitated the adsorption of reaction intermediates and thus enhanced the hydrogen evolution reaction performance. In particular, the optimized CoPv-MoxPv/CNT catalyst possesses an overpotential of 138 mV at a current density of 10 mA cm-2 and long-term stability for 24 h. This work offers insights and possibilities for the engineering and exploration of transition metal-based electrocatalysts through combining multiple synergistic strategies.

Dendrite‐Free Lithium‐Metal Batteries Enabled by 2D Lithophilic Conjugated Polymer on Separator

AbstractTacking issues of uncontrolled lithium dendrites formation with polymer‐based separator has a significant impact on the applications of lithium‐metal batteries. Here, porous poly(acrylonitrile) nanosheets (PPNS) enriched with conjugated C═C/C═N groups is designed on PP separator by spray‐coating. The conjugated molecular structure of PPNS affords high mechanical strength and thermal conductivity. Density functional theory (DFT) calculations confirm that polar N‐containing groups in PPNS derived from the cyclization of C≡N exhibit lithiophilic properties and effectively accelerate Li+ transport kinetics. Finite element simulation indicates PPNS with porous 2D nanosheet structure ensures a sufficient and uniform concentration of Li+ on the anode surface. Besides, a rich inorganic phase solid‐electrolyte interphase forms at the lithium metal interface under the induction of N‐containing groups, which further facilitates uniform lithium deposition. As a result, Li||LFP battery using PPNS@PP separator can stably cycle for 300 cycles at a high rate of 3C, with a capacity retention rate of 94.0%. Moreover, the Li||LFP pouch battery with PPNS@PP separator achieves steady cycling for 100 cycles at 0.2C, with a capacity retention rate of 95.7%.

Microwave-assistance boosted voltage window in oxygen-deficient MnCo2O4.5 for flexible asymmetric supercapacitors

Binder-free oxygen-vacancy-rich MnCo2O4.5 highly crystalline porous nanosheets directly grown on carbon cloth were successfully prepared via a time-saving microwave-assisted hydrothermal route. With the assistance of microwave, the ultrathin porous nanosheets structure, accompanied by rich oxygen vacancies in MnCo2O4.5, presents abundant interspace and pores with good conductivity, resulting in a high specific capacity (522.7 C g−1 at 1 A g−1) and satisfactory long-term stability (87.6 % capacity maintenance after 5000 cycles at 10 A g−1). More importantly, the stable potential window of the obtained MnCo2O4.5 electrode is extended to 1.05 V (0–1.05 V vs. Hg/HgO), surpassing the commonly reported potential window of MnCo2O4.5-based electrode materials, which typically falls below 0.75 V. Moreover, the assembled MnCo2O4.5/a-CC//AC all-solid-state asymmetric supercapacitor exhibits a wide stable voltage of 2.05 V, high energy density of 30.8 Wh kg−1 at 1025 W kg−1, with excellent long-term endurance (83.7 % capacity preservation after 6000 cycles at 5 A g−1) and mechanical flexibility. These results demonstrate the promising application of microwave-assisted oxygen-deficient MnCo2O4.5 in flexible wearable devices.

Defect-rich PdCo bimetallene constructed by a self-reduction strategy for enhanced ethanol oxidation reaction

Direct ethanol fuel cells have garnered considerable attention owing to their minimal pollution, high energy density and diverse fuel sources. However, the slow anodic ethanol oxidation reaction has limited its large-scale application. In this work, the green self-reduction method of Co2(CO)8 as precursor and reducing agent is used to design PdCo bimetallene for ethanol oxidation reaction. The ultra-thin porous nanosheet structure of PdCo bimetallene leads to its abundant defects, facilitating increased active sites and enhanced electrical conductivity. The findings demonstrate substantial enhancements in both the activity and stability of the catalyst. The mass activity of PdCo bimetallene reached 1.58 A mg−1, marking a 2.8-fold increase compared to Pd black. Moreover, the catalyst maintained no less than 98% of the initial current over five consecutive 4000 s chronoamperometric tests, highlighting its remarkable stability. This work provides a green self-reduction synthesis strategy for the preparation of defect-rich bimetallene for ethanol electrocatalytic applications.

Renewable lignin-derived heteroatom-doped porous carbon nanosheets as an efficient oxygen reduction catalyst for rechargeable zinc-air batteries

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.

Three-dimensional porous La(OH)3/g-C3N4 adsorption-photocatalytic synergistic removal of tetracycline.

La(OH)3/g-C3N4 composites were successfully synthesized via one-step calcination using urea, melamine, and La(NO3)3·nH2O as raw materials, and applied to UV-induced photocatalytic tetracycline (TC) removal. Comprehensive characterization by an X-ray diffraction (XRD), Fourier transform infrared reflection (FT-IR), high-resolution transmission electron microscope (HRTEM), and other techniques analyzed effects of La3+ doping, especially N vacancies and cyano groups as active sites. Compared to pure g-C3N4 and La(OH)3, synthesized La(OH)3/g-C3N4 composites exhibited a three-dimensional porous nanosheet structure with specific surface area of 83.62 m2/g and equilibrium TC adsorption capacity up to 285.59 mg/g; La(OH)3 doping significantly improved composite structure. After dispersing 10 mg La-CN-0.5 photocatalyst in 60 mL 40 mg/L TC solution, TC removal reached 91.08% in 30 min under UV irradiation, exhibiting excellent performance. Additionally, La-CN-0.5 showed significant adsorption-photocatalytic synergism, with the quasi-primary kinetic constant increased by 1.83-fold. The efficiency of high tetracycline (TC) concentration treatment through adsorption photocatalytic degradation by La-CN-0.5 was confirmed by the utilization of free radical trapping and electron spin resonance (ESR) tests. The significant involvement of ∙O2-, ∙OH, and h+ in this process was observed. These findings propose that the prepared La-CN-0.5 material exhibits a unique capability for adsorption photocatalysis, providing a promising approach for the efficient removal of high TC concentrations.

Facile synthesis of Zn0.5Cd0.5S nanosheets with tunable S vacancies for highly efficient photocatalytic hydrogen evolution.

In order to effectively improve the separation efficiency of photogenerated charge carriers and thus the photocatalytic activity, in this work, porous Zn0.5Cd0.5S nanosheets with a controlled amount of S vacancies were prepared by a multistep chemical transformation strategy using the inorganic-organic hybrid ZnS-ethylenediamine (denoted as ZnS(en)0.5) as a hard template. The amount of S vacancies and the morphology of the Zn0.5Cd0.5S nanostructures were tailored by adjusting the hydrolysis time. Furthermore, we report the observation of S vacancies in porous Zn0.5Cd0.5S nanosheets at the atomic level using spherical aberration-corrected (Cs-aberrated) transmission electron microscopy (Cs-corrected-TEM). The results revealed that Zn0.5Cd0.5S nanosheets with S vacancies absorb more visible light and generate more electron-hole carriers due to their porous nanosheet structure. At the same time, sulfur vacancies are introduced into the Zn0.5Cd0.5S nanosheets to capture the electrons generated by the light and further extend the lifetime of the carriers. As expected, the photocatalytic activity of Zn0.5Cd0.5S nanosheets prepared by 4 h hydrolysis is 20.5 times higher than that of Zn0.5Cd0.5S(en)x intermediates. Moreover, Zn0.5Cd0.5S-4h showed excellent cycling stability. This work provides a new strategy for the optimization of Zn0.5Cd0.5S photocatalysts to improve photocatalytic hydrogen evolution.

Interfacial electronic structure modulation enables PdAg/NiOx an advanced oxygen evolution electrocatalyst

Hydrogen production by electrolysis of water is one of the solutions to energy problems and environmental pollution. The design of efficient oxygen evolution electrocatalyst remains a challenging. One way to improve catalytic performance is to change the morphology and structure of the catalyst. Herein, a two-dimensional (2D) flake nano-flower heterostructured catalyst was designed on nickel foam (NF) substrate by simple hydrothermal and thermal annealing reactions. Benefiting from the porous nanosheet structure and synergistic effect between PdAg and NiOx, which facilitates electrolyte transport, the PdAg/NiOx nanosheets deliver a low overpotential (253 mV @ 10 mA cm−2) for oxygen evolution reaction (OER) and has excellent stability. In addition, the addition of PdAg alloy regulates the electronic structure of the active component Ni, which also makes for further improving the electrocatalytic OER performance. This work not only offers a promising strategy of in situ anchoring PdAg alloy on NiOx nanosheet but also provide a new way for the application of alloy heterogeneous interfaces to high performance OER catalysts.

Hierarchically crystalline copper borate nanosheets as a freestanding electrode for a hybrid supercapacitor

In this study, we have suggested a straightforward approach to fabricating a binder-free electrode of hierarchically crystalline copper borate (Cu-Bi) nanosheets grown on nickel foam using the Successive Ionic Layer Adsorption Reaction (SILAR) method. The best-performing electrode shows a remarkable specific capacitance (Cs) of 2002 Fg−1 at 1 Ag−1 and Cs retention of 85 % for 10,000 GCD cycles. The assembled CB/NF-2//AC device exhibits high cycling stability and achieves a high energy of 52.2 Whkg−1 at a power density of 2622.4 Wkg−1. Remarkably, it reached 152.7 Fg−1 at 2 Ag−1, and the device still has a high capacitance retention of 85 % for 10,000 cycles. This remarkable electrochemical activity could be attributed to: (i) the inherent defects of the prepared electrode via the existence of borates, providing straightforward interaction between the electrolyte and the active species; (ii) designing the hierarchical architecture that could provide a porous nanosheet structure, which generates accessible active sites for quick ion transport, boosting the Cs; (iii) the formation of crystalline Cu-Bi nanosheets, resulting in high stability and superior electrochemical performance compared to the previous amorphous borides; and (iv) the hybridization between the B 2p state and the multiple d-orbitals of transition metals, increasing the electron flow between the atoms. The current work suggests that the growth of hierarchically crystalline Cu-Bi on Ni foam using a low-cost and simple procedure could provide a practical approach to designing hybrid supercapacitors with outstanding electrochemical performance.

Porous nanosheets of TKX-50 by ice-templating strategy with excellent thermal decomposition and combustion properties

ABSTRACT Nanostructured energetic materials have attracted considerable research interests during the past decades because of their improved performances in thermal decomposition and combustion. In this work, a porous nanosheet structure of dihydroxylammonium 5, 5′-bistetrazole-1, 1′-diolate (TKX-50) has been fabricated by a facile ice templating strategy, which is based on the self-assembly of TKX-50 during rapid recrystallization. Thermal decomposition properties were determined by differential scanning calorimetry/thermogravimetry (DSC/TG) and TG-FTIR analyses. The laser-ignited and constant-volume combustions and mechanical sensitivity were conducted. As-prepared TKX-50 mainly presents porous nanosheets (NS-TKX-50) assembled by the secondary nanoparticles. NS-TKX-50 is typical of mesoporous materials with high specific surface area and pore volume. Compared with raw material, NS-TKX-50 exhibits lower thermal decomposition peak temperature and higher active energy. In thermal decomposition process, a great deal of gaseous products have been generated in a very narrow temperature range. These thermal decomposition features suggest a quick energy-release rate and high energy output. Contrary to incomplete combustion of raw material, NS-TKX-50 shows high-efficiency and self-sustaining laser-ignited combustion feature with a drastically decreased ignition threshold. And its pressurization rate and peak pressure are remarkably increased. Sensitivity results confirmed the visibly reduced impact and friction sensitivity of NS-TKX-50.

Facile synthesis of hierarchically ordered Mo2C/Co3Mo3C@C nanosheet heterostructure: A highly durable pH universal electrocatalyst for hydrogen evolution reaction and overall alkaline water splitting

Developing cost-effective, high-efficiency, earth-abundant electrode materials for hydrogen evolution reaction (HER) operating in wide pH range electrolytes is significant for large-scale hydrogen generation. However, the rational design of highly stable electrocatalysts with robust performance remains challenging. Herein, in-situ construction of hierarchically ordered Mo2C/Co3Mo3C nanosheet heterostructure (CMC/MC@C) is achieved by the simple pyrolysis method. The optimized Co1Mo1C/550 catalyst achieves a low HER overpotential of 86, 102, and 323 mV at 10 mA cm−2 current density in 1.0 M KOH, 0.5 M H2SO4, and 0.1 M PBS solutions, respectively, with robust durability over 48 h. Benefiting from the bifunctionality of Co1Mo1C/550, the electrocatalyst achieves a current density of 10 mA cm−2 at a low overpotential of 336 mV towards the oxygen evolution reaction (OER) and 1.597 V for overall water splitting in a 1.0 M KOH solution. The exceptional performance of the as-prepared catalyst is primarily attributable to the strong synergistic relationship between Co3Mo3C and Mo2C particles, hierarchically ordered porous carbon nanosheet structure, and superhydrophilic electrode surface, which not only provide rich exposed active sites but also boost the access of electrolytes and the diffusion of H2 bubbles, thereby effectively enhancing the HER and OER performances. This study offers a new approach to the rational design of various transition metal-based carbide electrode materials via the structural optimization strategy for reliable and efficient universal pH catalysts towards HER and overall alkaline water splitting.

Energy storage characteristics and mechanism of organic-conjugated polyanthraquinoneimide for metal-free dual-ion batteries

Organic materials have gained significant attention in the battery energy storage field due to their good reaction kinetics and designable properties. However, conventional organic materials typically exhibit poor cycling stability in dual-ion batteries because of their high solubility and low electron conductivity. Herein, an organic conjugated polyanthraquinoneimide (PAQI) with stacked layered porous nanosheet structures by a one-step solvothermal process. After polymerization, not only the solubility of PAQI in electrolytes was reduced, but also the utilization of the active site (C=O) was significantly increased to enhance the electronic conductivity. Moreover, PAQI also exhibited a high ion diffusion coefficient (0.946 × 10−10 ∼ 1.293 × 10−10 cm2 s−1) and showed excellent electrochemical performance as the anode for a metal-free dual-ion battery, with a discharge specific capacity of up to 128 mAh g−1 and a capacity retention rate of 80% after 200 cycles under a high rate of 2 C (1 C = 228 mA g−1). Meanwhile, cyclic voltammetry tests and reaction kinetic calculations revealed that PAQI was a pseudocapacitive storage mechanism combining diffusion control and surface capacitance processes (the capacitance contribution is 82.59 % at a scan rate of 0.9 mV s−1). These abundant stacked layered porous nanosheet structures provided a new route for research and development of the next-generation green metal-free dual-ion batteries.

One-step synthesis of S-doped C-vacancy g-C3N4 with honeycomb porous nanosheets structure for efficient visible-light-driven hydrogen evolution

A defective construction method was applied to design the molecular framework from the source and use the intermolecular forces of the raw materials to connect the long chains. The S-doped honeycomb g-C3N4 nanosheets were prepared by selective volatilization at elevated temperatures using melamine-tricyanuric acid-thiourea supramolecular liquid as precursor and template. In addition to significantly increasing the high surface area, the S-doped honeycomb g-C3N4 nanosheets also modify the band gap structure and shape. The introduction of the C defect also increased the number of reaction sites, improved visible light responsiveness, broadened the photoresponse range, and accelerated the segregated transfer of photogenerated carriers. The experimental results showed that the hydrogen production efficiency of S-PDCN-3 (The best sample of S-doped C-vacancy g-C3N4) is 23.78 mmol‧g−1‧h−1, which was 21.8 times that of BCN, namely Bulk g-C3N4 (1.1 mmol‧g−1‧h−1). After adding the photosensitizer (Erythrosin B) to the photocatalytic reaction system, EB + S-PDCN-3 (the best sample of S-doped honeycomb g-C3N4 nanosheets with the sensitizer) precipitated hydrogen up to 63.8 mmol‧g−1‧h−1, which was 17.78 times greater than the hydrogen production of the EB + BCN sample (3.59 mmol‧g−1‧h−1). Furthermore, the sample was observed to experience a reduction in band gap energy, an increase in electron density near VB and a reduction of H* adsorption–desorption barrier, all of which are essential for the enhancement of the hydrogen evolution reaction. Successful preparation of S-doped honeycomb g-C3N4 nanosheets provides a simple and efficient method for developing efficient g-C3N4 photocatalysts—potential applications in the development process of hydrogen energy and pollutant degradation.

CuO–ZnO catalyst decorated on porous CeO2-based nanosheets in-situ grown on cordierite for methanol steam reforming

Development of efficient and durable structured catalysts for hydrogen production by methanol steam reforming (MSR) is becoming extremely appealing owing to their low pressure drop and large open area. In this work, porous CeO2-based nanosheet array is in-situ grown on the surface of cordierite honeycomb ceramic by a simple hydrothermal approach. The generated porous nanosheet structure not only surpasses the obstacle of low specific surface area of cordierite (increasing from 4.4 to 252.6 m2 g-1), but also the peak area ratio of oxygen vacancies on the support surface rises from 19.7% to 29.7%, which are favorable to promote the catalytic activity and reduce by-product CO selectivity of structured catalysts in MSRreaction. Importantly, the structured catalysts formed by decorating CuO–ZnO catalysts on CeO2-based nanosheets via sol-gel combustion method remain porous structure, offering an ideal space for reactant entry and mass transfer diffusion, which facilitates reaction triggering and product discharge. The optimal structured catalyst achieves 100% methanol conversion at 260 °C without CO and the methanol conversion remains at 94.7% after 100 h of the reaction, exhibiting the excellent catalytic activity and durability. Thus, the structured catalyst has potential for industrial-scale preparation and application, especially for on-site hydrogen production in vehicles.

Ni sulfide nano-sheets as an efficient standalone electrode in direct ethanol fuel cells

BackgroundDirect alcoholic fuel cells such as DEFCs “direct ethanol fuel cells” have a high energy density and can potentially replace secondary batteries in portable applications. Two main challenges of the DEFCs are the low efficiency and the precious/expensive Pt-based electrodes. MethodsIn this study, a standalone nickel sulfide electrode was grown on the surface of nickel foam via hydrothermal method followed by hydrothermal ion exchange. Significant FindingsThe prepared electrodes have a highly porous nanosheet structure and demonstrated high ethanol oxidation activity. The electrode showed high stability and excellent mass transfer properties with a constant generation of current density of 100 mAcm−2 at 0.5 V, two times that of the Ni-layered double hydroxide and ten times that of nickel foam. The superior activity was due to the enhanced charge transfer of the nickel sulfide (confirmed by EIS (electrochemical impedance spectroscopy)) and the improved mass transfer of the highly porous nanosheet structure.