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<jats:title>Abstract</jats:title> <jats:p>High-performance oxygen electrocatalysts have attracted tremendous research attention because of their crucial roles in diverse renewable energy technologies such as metal-oxygen batteries, fuel cells, and water electrolyzers. In this study, a novel lattice manipulation strategy for the exploration of highly active electrocatalysts was established via self-assembly between exfoliated MXene and layered double hydroxide (LDH) nanosheets. Electrostatically-driven self-assembly between cationic Co-Fe-LDH and anionic MXene nanosheets yielded intimately-coupled Co-Fe-LDH-MXene nanohybrids with porous stacking structures and significant interfacial charge transfer. The self-assembled Co-Fe-LDH-MXene nanohybrid delivered excellent electrocatalyst functionality with a lowered overpotential of 252 mV at 10 mA cm-2 that is much better than those of the precursor Co-Fe-LDH and MXene nanosheets. The outstanding electrocatalytic activity of the self-assembled Co-Fe-LDH-MXene nanohybrid highlights a high efficacy of the self-assembly methodology in exploring high-performance electrocatalysts. In situ surface enhanced Raman scattering analysis during electrocatalysis found that the enhanced redox activity of metal cations achieved by intimate electronic coupling with ultrathin conductive MXene nanosheets mainly contributes to the improved performance of the Co-Fe-LDH-MXene nanohybrids for oxygen evolution reaction.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The demands of the energy storage market for better performing lithium-ion batteries (LIBs) are enormous and ever-increasing. Following this trend, new electrode materials with higher energy and power densities should be developed to reach the electrode requirements of next-generation batteries. With this in mind, we present a novel composite (CrPSe3-G-MWCNT@NiB) that combines diverse characteristics of the excellent Li storage properties of 2D layered chromium selenophosphate (CrPSe3), the high conductivity and specific surface area of carbon-based materials [graphite (G) and multi-walled carbon nanotubes (MWCNTs)], and the abundant coordinative unsaturated sites of Ni–B nanoflakes. The composites were synthesized via a process involving three stages: (i) a one-step high-temperature solid-phase 2D CrPSe3 preparation, (ii) high-energy ball milling integration with the carbon materials, and (iii) a fast interface chemical reduction coating with the Ni–B nanoflakes. It is demonstrated that the optimized CrPSe3-G-MWCNT@NiB composites exhibit a remarkable electrochemical response in lithium half-cells, delivering around 657 mAh g−1 after 200 cycles, as well as a significantly longer cycle life, higher rate capability and lower charge/discharge polarization in comparison with the pristine CrPSe3. Galvanostatic studies also revealed that the CrPSe3-G-MWCNTs@NiB electrode displays a remarkable electrochemical property, which enable its application in lithium full cells, with a capacity of 123 mAh g cathode−1 after 40 cycles and a high Coulombic efficiency (over 99.1%). Thus, the integration of the carbon materials and Ni–B nanoflakes into the presented composite makes it a particularly promising candidate anode for use in high performance LIBs.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The development of photo/electroactive catalysts sustainably producing hydrogen from water splitting and selectively hydrogen peroxide is of paramount importance to alleviate climate change effects. Herein, an anionic cobalt porphyrin (CoP) derivative is electrostatically interfaced with a positively charged modified MoS2, forming CoP/MoS2, which is accordingly employed as nonprecious photo/electrocatalyst for water oxidation reaction and selective H2O2 production. According to the results, CoP/MoS2 shows remarkable bifunctional photo/electrocatalytic performance for water oxidation (WOR) and 2e– pathway O2 reduction (ORR) reactions in alkaline electrolyte. Upon visible light irradiation, electrochemical measurements on a fluorine-doped tin oxide (FTO) coated glass electrode reveal an onset potential of 0.595 mV (ORR) and 1.575 mV (WOR) versus RHE, being improved by approximately 80 mV, in both cases, compared to the dark conditions. Notably, the use of the FTO set-up not only enabled us to evaluate the photo/electrocatalytic activity of the CoP/MoS2 nanoensemble but also mimics the practical conditions in photo/electrochemical devices. The outstanding bifunctional photo/electrocatalytic performance of CoP/MoS2 is attributed to (i) the use of CoP as versatile single-atom molecular catalyst and photosensitizer, (ii) the strong ion-pair interactions between cationic modified MoS2 and the anionic CoP derivative, which prevent aggregation, ensuring better accessibility of the reactants to single cobalt atom active sites, and (iii) the co-existence of 1T and 2H phase at modified MoS2, offering improved electrical conductivity and intrinsic electrocatalytic activity along with enhanced intraensemble electronic interactions upon illumination. This work is expected to inspire the design of advanced and low-cost materials for the sustainable production of renewable fuels. </jats:p>

<jats:title>Abstract</jats:title> <jats:p>Heterostructures of 2D materials using graphene and MoS2, have enabled both pivotal fundamental studies and unprecedented sensing properties. These heterosystems are intriguing when graphene and MoS2 are interfaced with 2D sheets that emulate biomolecules, such as amino-terminated oligoglycine self-assemblies (known as tectomers). The adsorption of tectomer sheets over graphene and MoS2 modulates the physicochemical properties through electronic charge migration and mechanical stress transfer. Here, we present a systematic study by Raman spectroscopy and tectomer-functionalised scanning probe microscopy to understand mechanical strain, charge transfer and binding affinity in tectomer/graphene and tectomer/MoS2 hybrid structures. Raman mapping reveals distinctive thickness dependence of tectomer-induced charge transfer to MoS2, showing p-doping on monolayer MoS2 and n-doping on multilayer MoS2. By contrast, graphene is n-doped by tectomer independently of layer number, as confirmed by X-ray photoelectron spectroscopy (XPS). The interfacial adhesion between the amino groups and 2D materials are further explored using tectomer-functionalised probe microscopy. It is demonstrated here that these probes have potential for chemically sensitive imaging of 2D materials, which will be useful for mapping chemically distinct domains of surfaces and the number of layers. The facile tectomer-coating approach described here is an attractive soft-chemistry strategy for high-density amine-functionalisation of AFM probes, therefore opening promising avenues for sensor applications.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>With the increasing demands of high-performance electronics, electronic devices generate more heat. Thus, efficient heat dissipation is crucially needed. Owing to its extremely good thermal conductivity, graphene is an interesting candidate for this purpose. In this paper, a two-step temperature-annealing process to fabricate ultrahigh thermal conductive graphene films (GFs) is proposed. The thermal conductivity of the obtained GFs was as high as 3826 ± 47 W m−1 K−1. Extending the time of high-temperature annealing significantly improved the thermal performance of the GF. Structural analyses confirmed that the high thermal conductivity is caused by the large grain size, defect-free stacking, and high flatness, which are beneficial for phonon transmission in the carbon lattice. The turbostratic stacking degree decreased with increasing heat treatment time. However, the increase in the grain size after long heat treatment had a more pronounced effect on the phonon transfer of the GF than that of turbostratic stacking. The developed GFs show great potential for efficient thermal management in electronics devices. Keywords: Graphene film, Ultrahigh thermal conductivity, Heat treatment time</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Graphitic carbon nitride (g-C3N4) is a visible light-responsive photocatalytic material with important application prospects in many fields. However, the interaction between g-C3N4 monolayers makes it easy to aggregate and precipitate in aqueous solutions, and it is necessary to prepare stable g-C3N4 aqueous dispersions for their applications. Here we propose a facile, green, and low-cost method for the preparation of stable g-C3N4 dispersions by ultrasonicating g-C3N4 in lysozyme (LYZ) solution. The LYZ was adsorbed on the surface of g-C3N4 through non-covalent interactions such as electrostatic interaction, hydrogen bonding and π-cation interaction to prevent the aggregation of g-C3N4 nanolayers. The LYZ/g-C3N4 could quickly re-form a uniform aqueous dispersion solution after freeze-drying, and exhibit good stability. Further, the results of photocatalytic sterilization showed that the assisted dispersion of LYZ enhanced the bactericidal activity of g-C3N4 and exhibited promising application prospects in the field of biomedicine and water disinfection. </jats:p>

<jats:title>Abstract</jats:title> <jats:p>The ability to switch between distinct states of polarization comprises the defining property of ferroelectrics. However, the microscopic mechanism responsible for switching is not well understood and theoretical estimates based on coherent monodomain switching typically overestimates experimentally determined coercive fields by orders of magnitude. In this work we present a detailed first principles characterization of domain walls (DWs) in two-dimensional ferroelectric GeS, GeSe, SnS and SnSe. In particular, we calculate the formation energies and migration barriers for 180° and 90° DWs, and then derive a general expression for the coercive field assuming that polarization switching is mediated by DW migration. We apply our approach to the materials studied and obtain good agreement with experimental coercive fields. The calculated coercive fields are up to two orders of magnitude smaller than those predicted from coherent monodomain switching in GeSe, SnS and SnSe. Finally, we study the optical properties of the compounds and find that the presence of 180° DWs leads to a significant red shift of the absorption spectrum, implying that the density of DWs may be determined by means ofsimple optical probes.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The development of efficient, low-cost, and eco-friendly catalysts for nitrogen fixation is essential and provides an alternative method to the traditional Haber–Bosch process. However, studies on thermal catalyst of nitrogen fixation mainly focus on metal-containing, and the microscopic mechanism of thermal reduction process is still limited. Herein, we explored an economic metal-free boron atom decorated poly(triazine imide) (B/PTI), a crystalline carbon nitride, as an excellent thermal catalyst of nitrogen fixation and proposed a substrate-hydrogen mechanism for the N2 thermal reduction reaction (NTRR). Our results reveal that the substrate hydrogen as the hydrogen source can promote the hydrogenation process with activation barrier of 0.56 eV, significantly lower than that of reported NTRR catalysts. Importantly, the B/PTI exhibits high turnover frequency (TOF), which is comparable to Fe, Ru, and Ti catalysts. Our work offers new insights into NTRR mechanism and provides an alternative solution for the sustainable ammonia synthesis. </jats:p>

<jats:title>Abstract</jats:title> <jats:p>Transition metal carbides or nitrides, collectively known as MXenes, are burgeoning two-dimensional (2D) materials for energy conversion and storage. The surface chemistry of MXenes could be specially tuned by the modified surface terminations, which directly influences their physicochemical properties. However, the in-depth study and understanding of the specific microstructure and the influence on the electrochemical performance of these terminations remain lacking. Herein, we present an accordion layered Ti2NTx MXene with -Cl and -O terminations obtained from copper chloride molten salt etching at a relatively low temperature. X-ray absorption fine structure (XAFS) and X-ray photoelectron spectroscopy (XPS) analyses reveal the formation of Ti-Cl and Ti-O bonds on the surface of Ti2NTx MXene. Density functional theory (DFT) calculations further suggest that the surface terminations tend to be replaced by -O terminations after Ti-Cl decoration, which implies promising lithium-ion storage performance due to the high lithium affinity of -O terminations. As a result, the Ti2NTx MXene based electrode delivers a high reversible capacity (303.4 mAh g-1 at 100 mA g-1), stable cycling capability (1200 cycles without capacity attenuation), and fast Li+ storage (52% capacity retention at 32 C). This work provides a new vision for MXene surface chemistry and an effective avenue to prepare high-performance nitride electrodes, expanding the diversity and controllability of the MXenes family.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Cataract surgery removes the diseased lens of the eye replacing it with an intraocular lens (IOL), restoring visual acuity. However, accommodation, the lens’ ability to provide dynamic change in focus, is lost. A number of accommodative intraocular lens (AIOL) designs have been considered although none have provided a truly effective clinical AIOL. Two-dimensional titanium carbide (Ti<jats:sub>3</jats:sub>C<jats:sub>2</jats:sub>T<jats:sub> <jats:italic>x</jats:italic> </jats:sub>) MXene has been used as a transparent conductive electrode within an AIOL feasibility study. Nevertheless, the potential for Ti<jats:sub>3</jats:sub>C<jats:sub>2</jats:sub>T<jats:sub> <jats:italic>x</jats:italic> </jats:sub> to repress excessive inflammation and promote wound healing following cataract surgery has not been considered. Cataract surgery can trigger chronic inflammation and epithelial-mesenchymal transition (EMT) in residual lens epithelial cells (LECs), producing a fibrotic mass across the optic known as posterior capsule opacification (PCO). With a large surface area and capacity for surface functionalisation, MXene has properties enabling a dual purpose AIOL design with an additional therapeutic role in the repression of pathways leading to PCO development. In this study, Ti<jats:sub>3</jats:sub>C<jats:sub>2</jats:sub>T<jats:sub> <jats:italic>x</jats:italic> </jats:sub> MXene was investigated to determine its impact on pathways leading to chronic inflammation and EMT using an in vitro LECs model. Ti<jats:sub>3</jats:sub>C<jats:sub>2</jats:sub>T<jats:sub> <jats:italic>x</jats:italic> </jats:sub> MXene was synthesised and characterised using UV-vis spectroscopy, dynamic light scattering and scanning electron microscopy. Changes in markers linked to inflammation and EMT in Ti<jats:sub>3</jats:sub>C<jats:sub>2</jats:sub>T<jats:sub> <jats:italic>x</jats:italic> </jats:sub>-treated LECs were measured using enzyme linked immunosorbent assays, quantitative polymerase chain reaction, scratch assay, RNA sequencing for whole-cell gene expression profiling and lipidomics analysis. Ti<jats:sub>3</jats:sub>C<jats:sub>2</jats:sub>T<jats:sub> <jats:italic>x</jats:italic> </jats:sub> significantly reduced the expression of pro-inflammatory cytokines by IL-1β primed LECs and did not advocate EMT through promoting a positive resolution of the wound healing response. This study supports the role of Ti<jats:sub>3</jats:sub>C<jats:sub>2</jats:sub>T<jats:sub> <jats:italic>x</jats:italic> </jats:sub> within an AIOL design with the potential to repress key developmental pathways leading to PCO.</jats:p>