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Nitrogen-rich ultra-thin (1–2 nm thick) layers in diamond produced by high-temperature nitrogen ion (N2+) implantation at low N2+ energies studied by in situ x-ray photoelectron spectroscopy are reported. Nitrogen bonding at the subsurface region and its thermal stability, as well as structural defects in polycrystalline diamond (PCD) implanted with 200, 500, and 800 eV N2+ at room temperature (RT) and 600 °C at an ion dose of 4.5 × 1014 ions/cm2, are investigated. Implantation at RT leads to nitrogen bonding at interstitial and substitutional sites in the diamond lattice, which is associated with the C–N/C=N bond, lower intensity of the C≡N (nitrile-like) component associated with nitrogen bonding with carbon defects, and quaternary nitrogen. The relative composition of these chemical states varies with implantation energy, temperature, and post-implantation annealing temperature. Upon annealing the RT implanted layers above 500–600 °C, the interstitial nitrogen converts to substitutional nitrogen. This process competes with nitrogen desorption. The thermal stability of nitrogen increases with implantation energy. Implantation at 600 °C at 800 eV resulted in a significantly lower concentration of nitrile-like bonds and a lower density of structural defects compared to RT implantation at the same energy. These effects are associated with dynamic annealing, which becomes more significant at higher implantation energies. Upon high-temperature implantation, nitrogen mostly populates directly substitutional sites. Nitrogen implantation at low energy and high temperature may be a viable way to nitride diamond surfaces with reduced density of defects where nitrogen is selectively bonded to substitutional sites. Finally, a comparison between nitrogen implantation into PCD and Diamond (100) [Di(100)] surfaces is presented. [ABSTRACT FROM AUTHOR]

Amorphous carbon nitride (a-CNx) films, prepared by reactive radio frequency magnetron sputtering, exhibit unique characteristics under visible light irradiation, referred to as photoinduced deformation. This phenomenon represents an energy conversion system wherein photon energy transforms into kinetic energy. The chemical bonding structure of a-CNx films was analyzed using near-edge x-ray absorption fine structure (NEXAFS) at the NewSUBARU synchrotron facility of the University of Hyogo, Japan. This analysis aimed to elucidate the mechanisms behind the photoinduced deformation observed in a-CNx films. Three variants of a-CNx films, displaying varying degrees of photoinduced deformation, were deposited using a graphite target and nitrogen gas under different deposition temperatures. The NEXAFS spectra of the a-CNx films with substantial photoinduced deformation showed changes under light irradiation from a Xe lamp (directed through an optical window within the NEXAFS chamber). Specifically, the peaks corresponding to the 1s to π* transition related to C—C and 1s to σ* transition related to C—N bonds exhibited high sensitivity to visible light irradiation. Simultaneously, the N K-edge spectra associated with the 1s to π* transition, attributed to the N—C bond, exhibited a slight intensity decrease. Conversely, the C K-edge spectrum in the a-CNx films displaying minimal photoinduced deformation remained unchanged under visible light irradiation. The N K-edge spectra maintained a consistent shape under both visible light and dark conditions. [ABSTRACT FROM AUTHOR]

Successful synthesis of novel high entropy ceramic (HEC) for ultra-high temperature application classes, namely, borides, carbides, and nitrides, has been experiencing a bottleneck in having a suitable design and successful synthesis strategy. Producing high-entropy ultra-high-temperature ceramics from their oxides offers a major processing benefit, while employing a design approach using machine learning enhances the efficiency of the formation of single-phase HECs. In this regard, we propose a generalized strategy to generate a semi-synthetic database for each of these classes using literature data and atomic environment mapping-based structure plots, which can further be used to build machine learning models. The imbalance of the dataset was addressed using adaptive synthetic sampling and the edited nearest neighbors technique. The trained models are able to accurately predict over 90% of the single-phase chemistry for each of the classes. Furthermore, a few compositions representing these classes were successfully synthesized from the corresponding oxide mixture to validate the effectiveness of the proposed strategy. [ABSTRACT FROM AUTHOR]

MoSi2N4 is a two-dimensional ternary nitride semiconductor that has attracted attention for its excellent mechanical and thermal properties. Theoretical studies predict that zigzag edges of this material can host magnetic edge states and Dirac fermions, but the stability of such edges has not been examined. Here, we present a density functional theory study of the electronic and thermodynamic properties of MoSi2N4 edges. We develop a (partial) ternary phase diagram that identifies a region of chemical potentials within which MoSi2N4 is stable over competing elemental or binary phases. Based on this phase diagram, we determine the thermodynamic stability of several armchair and zigzag edges and elucidate their electronic structures. Bare zigzag edges, predicted to host exotic electronic states, are found to be substantially higher in energy than armchair edges and, thus, unlikely to occur in practice. However, with hydrogen passivation, these zigzag edges can be stabilized relative to their armchair counterparts while retaining metallicity and magnetic order. Our analysis provides a solid thermodynamic basis for further exploration of MoSi2N4 in nanoscale electronics and spintronics. [ABSTRACT FROM AUTHOR]

MoSi2N4 is a two-dimensional ternary nitride semiconductor that has attracted attention for its excellent mechanical and thermal properties. Theoretical studies predict that zigzag edges of this material can host magnetic edge states and Dirac fermions, but the stability of such edges has not been examined. Here, we present a density functional theory study of the electronic and thermodynamic properties of MoSi2N4 edges. We develop a (partial) ternary phase diagram that identifies a region of chemical potentials within which MoSi2N4 is stable over competing elemental or binary phases. Based on this phase diagram, we determine the thermodynamic stability of several armchair and zigzag edges and elucidate their electronic structures. Bare zigzag edges, predicted to host exotic electronic states, are found to be substantially higher in energy than armchair edges and, thus, unlikely to occur in practice. However, with hydrogen passivation, these zigzag edges can be stabilized relative to their armchair counterparts while retaining metallicity and magnetic order. Our analysis provides a solid thermodynamic basis for further exploration of MoSi2N4 in nanoscale electronics and spintronics. [ABSTRACT FROM AUTHOR]

Improving piezoelectric and ferroelectric responses of group III-nitrides is desired for their potential applications in the emerging microelectromechanical-based systems. One possible approach to realize the optimization and control of functionalities is to bring together compounds with different properties to form the ordered multilayer superlattices. In this work, we systematically investigate the phase stability, piezoelectricity, and ferroelectricity in a class of wurtzite-structure-derived nitride superlattices with a periodic alternation of chemically and/or structurally different layers. The structural heterogeneity and phase stability of the ordered wurtzite-structure-derived superlattices are intimately related to the ionic radii mismatch between the substitutional compounds and the parent nitrides. Moreover, the internal structural distortion of the nitride superlattices has a crucial impact on the ferroelectricity and piezoelectricity, namely, piezoelectric and ferroelectric responses become increasingly enhanced as the buckled atomic layers becomes flatter. This work offers fundamental physical insights into the structure–property relationships in nitride superlattices and may propose some material design strategies for achieving high-performance materials with desired responses. [ABSTRACT FROM AUTHOR]

Gallium nitride (GaN) and aluminum nitride (AlN), as examples of third-generation semiconductors, have attracted significant interest due to their remarkable physical attributes, including a wide bandgap, high breakdown voltage, exceptional chemical stability, and high thermal conductivity. These characteristics render GaN and AlN highly promising for use in power and (opto)-electronic devices. Consequently, there is a growing demand for high-quality GaN and AlN crystals on the centimeter scale. As the dislocation density in these materials decreases, the need for a reliable method of dislocation characterization becomes more pressing. Synchrotron radiation x-ray topography (SR-XRT) has emerged as a superior, nondestructive technique for the precise characterization of crystal defects. This review briefly introduced the principle of XRT, and its application in the analysis of dislocations in GaN and AlN crystals is summarized. By examining the relationship between the SR-XRT image contrast and the Burgers vectors of dislocations, it is possible to categorize wafer dislocations and determine the magnitude and direction of Burgers vectors. Additionally, SR-XRT facilitates the analysis of interactions between dislocations in GaN and AlN crystals. These analyses are instrumental in advancing the development of superior crystals. This review concludes with a discussion of the current challenges faced by SR-XRT and a projection of its future applications in characterizing third-generation semiconductor crystal materials. This review offers significant guidance for the characterization of nitride crystal defects using SR-XRT. [ABSTRACT FROM AUTHOR]

Thorium nitrides have been the topic of intense studies due to their prospective applications as advanced nuclear fuels. The phase diagram of the Th–N scheme, however, continues unknown at low temperatures and extremely high pressures. In this article, we examine the Th–N system's phase diagram up to 300 GPa from the first-principle approach using universal structure predictor: evolutionary Xtallography (USPEX) method. Apart from the experimentally observed phase (ThN, Th2N3, and Th3N4), there are several unique chemical stoichiometries, i.e., ThN3, ThN4, ThN6, ThN8, ThN10, and ThN12 are found to have stability fields on the Th–N phase diagram at pressure of 3.0, 32, 100, 42, 28, and 236 GPa along with previously predicted composition ThN2 at 3.5 GPa. The structural stability of the predicted compositions is further assessed by evaluating the elastic and dynamic stability. Out of all above mentioned compositions, ThN3 is possibly a metastable one at 0 GPa. Electronic structure calculations predict that all newly discovered compositions are metallic except ThN10, which is semi-metallic at high pressures. Further, we predict that ThN4 and ThN6 have high electron–phonon coupling constant of 1.874 and 0.894 with Tc around 21.22 and 25.02 K, respectively, at 100 GPa. [ABSTRACT FROM AUTHOR]

Wurtzite ScxAl1−xN/GaN (x = 0.13–0.18) multi-quantum wells grown by molecular beam epitaxy on c-plane GaN are found to exhibit remarkably strong and narrow near-infrared intersubband absorption in the technologically important 1.8–2.4 μm range. Band structure simulations reveal that, for GaN wells wider than 3 nm, the quantized energies are set by the steep triangular profile of the conduction band caused by intrinsic polarization fields. As a result, the intersubband transition energies provide unique and direct access to essential ScAlN polarization parameters. Measured infrared absorption indicates that the spontaneous polarization difference of the presumed lattice-matched Sc0.18Al0.82N/GaN heterostructure is smaller than the theoretically calculated value. The intersubband transition energies are relatively insensitive to the barrier alloy composition indicating negligible variation of the net polarization field in the probed 0.13–0.18 Sc composition range. [ABSTRACT FROM AUTHOR]

A first-principles-based lattice model is applied to investigate the ordered phases of mixed group-III nitride ternary alloys. The model surveys the atomistic configurations with the lowest formation enthalpy for a wide range of compositions. We found novel ordered phases in wurtzite structures having specific compositions of three- and four-sevenths molar fractions of group-III cations. The configurations of group–III atoms on cation sites in those phases consist of a characteristic fragment of the ordered phases of one-third and one-half ordered phases that were previously reported. The simulation results indicate that group-III cations in ternary nitrides follow spatial positioning "atomistic distancing rules" that can be described by the pairwise interaction energy of group-III cations to realize the stabilities of the ordered structures. To minimize the formation enthalpy of a mixed crystal, the minor B, Al, Ga, and In atoms on cation sites remain neither too close to nor too distant from each other, allowing those ordered phases to be realized. [ABSTRACT FROM AUTHOR]

Scandium nitride (ScN) is an attractive material for electronic applications due to its high n -type conductivity. Native defects and unintentional impurities may limit its electron concentration and reduce its mobility; therefore, it is important to control their formation and incorporation. Hydrogen and oxygen are unintentional impurities that are commonly present during growth and processing. They act as shallow donors in ScN and hence may be regarded as harmless or even favorable to achieving n -type conductivity. Here we show, using state-of-the-art first-principles calculations, that these impurities can be detrimental because they readily form complexes with scandium vacancies (V Sc ). Isolated V Sc have relatively high formation energies and thus have low concentrations and little impact on electronic properties. However, complexes between V Sc and either hydrogen or oxygen form more readily than the pristine vacancy and will act as both compensating and scattering centers. Our results point to the importance of controlling the incorporation of hydrogen and oxygen in ScN (and AlScN alloys) to avoid degradation of the electronic properties. [ABSTRACT FROM AUTHOR]

The surface optical (SO) phonon replica in photoluminescence (PL) spectroscopy of nitride nanowires (NWs) was theoretically investigated in this study. The dispersive relationships of SO phonon mode in anisotropic wurtzite (WZ) and isotropic zinc-blende (ZB) crystal structure NWs with circular and square cross sections (CSs) were derived within the framework of the dielectric continuum model. Based on the energy and momentum conservation laws, a constraint relationship between the frequency and wave-number was constructed for SO phonon-assisted excitonic PL spectra in the NW structure. By combining the dispersive and constraint relationships, the frequency and wave-number of the SO phonon replica in the PL spectra could be determined. The WZ and ZB crystal structures of nitride semiconductor were considered. The influences of surface factors including the CS shape, dielectric medium, and environment temperature on the frequency and photon wavelength of the band-edge emission of the SO phonon replica were studied in detail. Numerical results reveal that the crystal structure, surface factors, and environment temperature greatly affect the frequency and photon wavelength of the band-edge emission of the SO phonon replica. The calculated results for the photon wavelength agree well with the experimental values of the SO phonon replica in AlN NWs. The results of the dielectric effect obtained here are also supported by previous experimental and theoretical results for nitrides and other semiconductor NWs. The present theoretical scheme and numerical results can be used to analyze and design the SO phonon replica in PL spectra of nanostructures. [ABSTRACT FROM AUTHOR]

Al0.85Sc0.15N thin films, about 920 nm thick, have been deposited on the Si (001) substrate by reactive magnetron sputtering at 600 °C. X-ray diffraction and pole-figure measurements revealed [0002]-oriented texture structures of the nitride films without any phase separations before and after cyclic annealing at 600–900 °C for up to 48 min. Cross-sectional studies by transmission electron microscopy and energy dispersive x-ray analysis revealed an intermediate Al0.85Sc0.15N layer of ∼24.6 nm thick with smaller grains and tilted [0002]-orientations compared to its overlayer, i.e., a nucleation layer (NL), on the Si substrate. After annealing, apparent morphological changes have been observed at the near-interface regions, including the NL, the NL/Si interface, and the Si substrate, rather than in the Al0.85Sc0.15N overlay. Undesired oxygen has been observed in the nitride film and its composition increased during post-growth thermal annealing without forming oxides. These observations shed new light on crystal growth and post-growth thermal annealing of AlScN toward their high-performance piezoelectric applications. [ABSTRACT FROM AUTHOR]

Using the Full Potential Linear Augmented Plane Wave and the pseudo-potential method based on the Density Functional Theory, we investigate the physical properties of two-dimensional (2D) boron nitride, carbon nitride, and boron carbide as well as their ternary system boron carbon nitride (BCN). The structural and optoelectronic properties are determined and discussed in detail with available theoretical and experimental results. We show that the studied physical properties are influenced and tunable by atom concentration. A high concentration of nitrogen (> 50%) disturbs the honeycomb structure of binary and ternary alloys. Additionally, the optoelectronic properties are very sensitive to the amount of boron and nitrogen atoms. The zero bandgap is only conserved for B3C12N3 and B6C6N6 ternary systems. A large bandgap was observed for B9N9 (∼3.9 eV) and a moderate one for B6N12 and B3N15 (∼2 eV). The coexistence of boron, carbon, and nitrogen atoms with different concentrations has important optical properties as they can absorb light in all spectra. However, they have more active absorption in the ultraviolet than visible regions. It is more interesting to use ternary BCN than binary or pristine alloys with tunable optoelectric properties, by varying the nitrogen content in nanodevices. [ABSTRACT FROM AUTHOR]

Inspired by the single-bonded nitrogen chains stabilized by tetravalent cerium, pentavalent tantalum, and hexavalent tungsten atoms, we explored the possibility of single-bonded nitrogen polymorphs stabilized by trivalent lanthanum ions. To achieve this, we utilized the crystal structure search method on the phase diagram of binary La–N compounds. We identified three novel thermodynamically stable phases, the C2/c LaN3, P-1 LaN4, and P-1 LaN8. Among them, the C2/c phase with infinite helical poly-N6 chains becomes thermodynamically stable above 50 GPa. Each nitrogen atom in the poly-N6 chain acquires one extra electron, and the spiral chain is purely single-bonded. The C2/c phase has an indirect band gap of ∼1.6 eV at 60 GPa. Notably, the band gap exhibits non-monotonic behavior, decreases first and then increases with increasing pressure. This abnormal behavior is attributed to the significant bonding of two La–N bonds at around 35 GPa. Phonon spectrum calculations and AIMD simulations have confirmed that the C2/c phase can be quenched to ambient conditions with slight distortion, and it exhibits excellent detonation properties. Additionally, we also discovered armchair-like nitrogen chains in LaN4 and the armchair and zigzag-like mixed nitrogen chains in LaN8. These results provide valuable insights into the electronic and bonding properties of nitrides under high pressure and may have important implications for the design and development of novel functional materials. [ABSTRACT FROM AUTHOR]

A memristor is a two-terminal electrical component with the scope of future computing applications and analog electronics. In this report, bismuth sulfide decorated one-dimensional carbon nitride nanotube was synthesized and characterized with various analytical techniques. The electrical property of the synthesized material was measured using a two-terminal metal–insulator–metal type of device that exhibited the resistive switching characteristics with the ON to OFF ratio of 2 × 103. The electron transport mechanism of the device was followed by Schottky emission and Poole–Frenkel emission for a low conductance state and Ohmic conduction behavior at the high conductance state. A decrease in the trap depth was identified in the simulation study with increasing applied potential and that supported the proposed mechanism. Read endurance and retention behavior of the device are stable in nature, supported by the statistical analysis. Furthermore, a hybrid logic gate was designed using two identical memristors, one CMOS inverter, one resistor, one voltage divider, and a buffer gate. The designed logic gate exhibited stable nand and nor gate operation based on the control signal. [ABSTRACT FROM AUTHOR]

A series of inorganic acid post-treated carbon nitride was synthesized to regulate the electronic structure, surface properties and then improve the photocatalytic activity. Carbon nitride displayed a thinner and smaller nanosheet structure after acid post-treatment, which could provide more exposed active sites and improve the charge carrier separation. The electronic band gap structure revealed that the phosphoric acid-treated sample (HP-CN) had a more positive valence band edge, endowing it with a higher oxidation ability. Furthermore, electron spin resonance (EPR) and transient photoinduced voltage (TPV) analyses demonstrated that the acid-treated carbon nitride had a higher electron–hole pair separation and transfer efficiency, thus boosting the photocatalytic performance. HP-CN possessed an optimal removal efficiency of 87.7% towards Reactive Brilliant Red X-3B (RBR X-3B), which was 1.62 times that of g-C3N4. Moreover, HP-CN showed an outstanding stability and satisfactory ability to remove RhB (rhodamine B) and TC (tetracycline), proving its potential application in environmental remediation. The photocatalytic mechanism measurement indicated that photogenerated h+, ˙O2− and ˙OH played critical roles during photocatalytic RBR X-3B decomposition. [ABSTRACT FROM AUTHOR]

The use of red fluorescent powder derived from nitrides and oxides in warm white LEDs is a pressing concern due to its lower quantum efficiency. Fluoride red phosphors activated by Mn4+ ions show promising potential for application in white light-emitting diodes (LEDs) due to their distinctive narrowband red emission and broad blue excitation, along with the relatively mild synthesis conditions required. However, the quantum efficiency of early Mn4+-doped fluoride phosphors was not optimal, highlighting the importance of identifying a suitable preparation method and matrix. Here, we introduce an efficient and thermally stable red fluoride phosphor, Cs 2 SiF 6 :Mn4+, which demonstrates a remarkable quantum efficiency of 98.32 % achieved through ion exchange techniques. However, even at a temperature of 423 K, the luminous intensity still maintained at 95 % of that under room temperature conditions. By incorporating Cs 2 SiF 6 :Mn4+ as a red emitter, a stable 10 W high-power warm white LEDs with a luminous efficiency of approximately 126.1 lm/W can be realized. These findings underscore the significant potential of the red phosphor Cs 2 SiF 6 :Mn4+ in advancing high-performance, high-power warm white LEDs. [ABSTRACT FROM AUTHOR]

Organic photodetectors (OPDs) hold immense promise for optoelectronic applications. Here a zero‐biased, high‐performance organic photodetector employing a 2D organic heterostructure is introduced. The structure combines carbon quantum dots (CQDs) with nitrogen self‐doped graphitic carbon nitride (g‐C3N4+) and is tested for alternating current (AC) photodetection on an interdigitated electrode platform. The study reveals extraordinary performance driven by the synergistic effects of efficient charge excitation, separation, and emission within the 2D/2D CQD/g‐C3N4+ heterostructure, leveraging mechanisms of photoconduction, photogating, and fluorescence. A unique convergence to similar rise and decay times in the order of 2.9 ms is observed at higher frequencies in the visible (Vis) spectrum. Benchmarking against state‐of‐the‐art OPDs shows ultrahigh specific detectivity (4.60 × 1018 Jones), ultrahigh responsivity (1.43 × 107 A W−1), high external quantum efficiency (43 × 107%) at an optical intensity of 3.56 × 10−4 mW cm−2 and a wavelength of 405 nm while delivering competitive performance at 532 and 635 nm as well. Moreover, a large linear dynamic range of 86–162 dB in the Vis spectrum is obtained. These enhancements promise development of a new generation of OPDs to advance light sensing and imaging applications at high frequency, marking a significant milestone in optoelectronic device engineering. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide (H2O2) plays a crucial role in various applications, such as green oxidation processes and the production of high‐quality fuels. Currently, H2O2 is primarily manufactured using the indirect anthraquinone method, known for its significant energy consumption and the generation of intensive by‐products. Extensive research has been conducted on the photocatalytic production of H2O2via oxygen reduction reaction (ORR), with polymeric carbon nitride (PCN) emerging as a promising catalyst for this conversion. This review article is organized around two approaches. The first part main consists of the chemical optimization of the PCN structure, while the second focuses on the physical integration of PCN with other functional materials. The objective is to clarify the correlation between the physicochemical properties of PCN photocatalysts and their effectiveness in H2O2 production. Through a thorough review and analysis of the findings, this article seeks to stimulate new insights and achievements, not only in the domain of H2O2 production via ORR but also in other redox reactions. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g‐C3N4) assisted photocatalytic production of hydrogen peroxide (H2O2 has already attracted the interest of many researchers due to its environmental sustainability. Nevertheless, the inherent drawbacks of g‐C3N4 limit its progress. Metal‐free modification strategies, including nanostructure design, defect introduction, doping, and heterojunction construction, have been developed to improve the efficiency of g‐C3N4 photocatalytic H2O2 production. Compared to metal modification, metal‐free strategies avoid the use of precious metals and the leaching of heavy metal ions, which have the advantages of good stability and environmental friendliness. However, a comprehensive review of H2O2 production from g‐C3N4 modified by metal‐free strategies is still lacking. This review first recaps the mechanism of photocatalytic H2O2 production by g‐C3N4, including photoexcitation, carrier separation and redox reactions. Then, the perspective advances in metal‐free modified g‐C3N4 photocatalysts are presented, with the special focus on the kernel connection between different strategies and mechanism based on the pivotal stages of H2O2 production. Subsequently, recent applications of g‐C3N4‐based photocatalysts for in situ generated H2O2, mainly including water purification and organic synthesis, are briefly discussed. Finally, the prospects of g‐C3N4‐based photocatalysts are envisioned with the hope that it will have "something to do" in the field of H2O2 production. [ABSTRACT FROM AUTHOR]

[Display omitted] Despite the excellent photocatalytic activity under visible light, graphitic carbon nitride (g-C 3 N 4) exhibits a high overpotential for hydrogen evolution. To address this issue, cocatalysts have been utilized to modify g-C 3 N 4. However, the use of high-performance cocatalysts typically involves noble metals such as platinum and palladium, which are cost-prohibitive for practical applications. Therefore, the development of efficient and cost-effective cocatalysts is crucial for advancing photocatalysis. In this study, we synthesized a new Ni-based cocatalyst, nickel thiocarbonate (NiCS 3), to enhance the photocatalytic hydrogen evolution reaction (HER) on g-C 3 N 4. The NiCS 3 /g-C 3 N 4 composite demonstrated a significantly increased hydrogen evolution rate of 951 μmol·h−1·g−1 under visible light, representing more than a 105-fold improvement compared to pure g-C 3 N 4. Theoretical calculations suggested that the enhanced performance in photocatalytic hydrogen production can be attributed to the generation of a built-in electric field within the composite, facilitating efficient charge carrier separation and migration. Additionally, the C site in NiCS 3 provides a favorable Gibbs free energy of adsorbed H* (Δ G H ∗ ). This work underscores the potential of NiCS 3 as a viable alternative to precious metals in photocatalytic hydrogen production using g-C 3 N 4. [ABSTRACT FROM AUTHOR]

I-line stepper is widely used in large scale device manufacturing with limited achievable critical dimension by itself. With the aid of the spacer sidewall, the critical dimension can be further shrunk down. Spacer sidewall aided process necessitates an additional deposition-etching process, which inevitably results in process related damage under the gate. This paper proposes an optimized spacer sidewall aided gate patterning procedure for 0.15 μm GaN High Electron Mobility Transistors (HEMTs) fabrication. The process is proved to be effective in improving device performance compared to conventional sidewall process by keeping first Si-rich SiN passivation layer integrity at the gate edge. Interface trap density (Dit) and mobility were extracted for both conventional sidewall process and the optimized one with different passivation layers at the gate edge, demonstrating a lower Dit and higher mobility using the optimized process with enhanced device performances, such as higher current, breakdown voltage, and stress state characteristics, compared to the conventional process, which is promising for mass production of 0.15 μm GaN HEMTs. [ABSTRACT FROM AUTHOR]

MicroLEDs, particularly when integrated with CMOS microelectronics, represent a significant advancement in nitride technology. While large-area, high-power LEDs for solid-state lighting have seen extensive optimization, microLEDs present unique fabrication and characterization challenges. Utilizing standard CMOS design and foundry services for silicon driver electronics, a new hybrid interconnect technology must be developed for chip–chip or wafer–wafer integration, necessitating much higher lateral resolution than current bonding technologies. Beyond display technology, microLED integration opens avenues for groundbreaking applications such as highly efficient nanosensors, miniaturized optical neuromorphic networks, and robust chip-based microscopy. This paper explores recent advancements in nitride/CMOS hybrid modules, providing an overview of current technologies and future possibilities in this dynamic field. [ABSTRACT FROM AUTHOR]

Polymeric carbon nitride (CN) has emerged as a promising photoanodic material in water‐splitting photoelectrochemical cells (PEC). However, the current deposition methods of CN layers on substrates usually include a long heating process at 500−550 °C, which might cause sublimation or decomposition of the CN monomers and destruction of the substrate, leading to a nonuniform CN film. Herein, a simple, fast, and scalable energy‐economic procedure to synthesize homogenous CN films is introduced. The predesigned CN monomers film is subjected for several minutes to higher temperatures than the standard calcination procedure. The short heating process allows the formation of a uniform CN layer, with excellent contact with the substrate and good activity as a photoanode in PEC. The optimal CN photoanode reaches photocurrent densities of ≈200 μA cm−2 at 1.23 versus reversible hydrogen electrode in neutral and acidic solutions and 120 μA cm−2 in a basic solution. [ABSTRACT FROM AUTHOR]

Oxide/Nitride/Oxide/Nitride (ONON; SiO2/SiNx/SiO2/SiNx) stacked structure is widely used in the 3D vertical structure of semiconductor cells. Previously, to form a 3D cells, photoresist (PR) was patterned and repeatedly trimmed on the top of ONON after the etching of one ON layer. Due to the time-consuming process of etching layer-by-layer of ON layer, two-step etch processing using C4F8-based or C4F6-based gases composed of maskless ONON stack feature etching and followed one ON layer-by layer etching by PR trimming in the ONON stack feature are employed these days. However, the two-step etching method resulted in poor etch profiles of maskless ONON stack feature in addition to high global warming potential of C4F8 and C4F6. In this study, we investigated the etching of maskless ONON stack feature using C4H2F6-based gas having a low global warming potential and the effects of C4H2F6-based gas on the etch characteristics of maskless ONON stack feature such as etch rate, etch profile, change in critical dimensional (CD), and etch selectivity between SiO2 and SiNx have been investigated. C4H2F6-based gas showed the highest etch rates compared to C4F6 and C4F8-based gases in addition to the etch selectivity of ~ 1:1 between SiO2 and SiNx due to hydrogen included in the gas structure. In addition, the change in horizontal CD was lower in the order of C4H2F6, C4F6, and C4F8-based gases due to the more effective sidewall passivation in the order of C4F8, C4F6, and C4H2F6-based gases. The thicker carbon-based polymer layer on the sidewall also played an important role in maintaining the shape of the top edge shape of maskless ONON stack feature when etching a line feature in an environment without a mask. [ABSTRACT FROM AUTHOR]

The research for wurtzite‐type ternary nitride semiconductors containing earth abundant elements with a stoichiometry of 1 : 1 : 2 was focused on metals like Mg or Zn, so far. The vast majority of these Grimm–Sommerfeld analogue compounds crystallize in the β‐NaFeO2 structure, although a second arrangement in space group Pmc21 is predicted to be a viable alternative. Despite extensive theoretical and experimental studies, this structure has so far remained undiscovered. Herein, we report on BeGeN2 in a Pmc21 structure, synthesized from Be3N2 and Ge3N4 using a high‐pressure high‐temperature approach at 6 GPa and 800 °C. The compound was characterized by powder X‐ray diffraction (PXRD), solid state nuclear magnetic resonance (NMR), Raman and energy dispersive X‐ray (EDX) spectroscopy, temperature‐dependent PXRD, second harmonic generation (SHG) and UV/Vis measurements and in addition also compared to its lighter homologue BeSiN2 in all mentioned analytic techniques. The synthesis and investigation of both the first beryllium germanium nitride and the first ternary wurtzite‐type nitride crystallizing in space group Pmc21 open the door to a new field of research on wurtzite‐type related structures. [ABSTRACT FROM AUTHOR]

A systematic investigation of the electrochemical iron nitride synthesis in a LiCl/KCl salt melt at 723 K shows an optimum of ϵ -Fe 3 N 1 + x formation in the range of 2.2 to 2.3 V and for γ ′ -Fe 4 N between 2.4 and 2.5 V enabling the control of the desired iron nitride phase by setting the supplied terminal voltage. The product formation of iron nitrides starts when the electrochemical window is reached, which could be verified by linear sweep voltammetry. Hence, a maximum of nitrogen content in the formed iron nitride phases is observed for 2.27 V. During elongated synthesis periods, convection emerges as the predominant transport mechanism hindering an accelerated reaction rate with higher overpotential applied. Real-time analysis of the background current allows conclusions about the remaining nitride concentration. Additionally, there is concurrent iron nitride formation at the electrode surface through nitride adsorption and autonucleation-induced precipitation of iron and nitride ions. The analysis of the amount of sediment in comparison to the layer thickness of the nitrided working electrode suggests that the autonucleation mechanism dominates over the adsorption mechanism with increasing overpotential and can be further enhanced by this feature. [ABSTRACT FROM AUTHOR]

3D printed mixed matrix membrane (MMM) thin film, as a novel adsorbent, was introduced for the extraction of two steroid hormones from wastewater and tap water samples before their determination by high-performance liquid chromatography. The designed adsorbent was fabricated as thin film utilizing digital light processing (DLP) 3D printing. The thin film was made of acrylate photo resin, graphitic carbon nitride (g-C3N4), and polyvinylpyrrolidone and its application was investigated for thin film microextraction of 17β-estradiol (E2) and estrone (E1). The morphology of the 3D printed film surface and its chemical changes were studied using field emission scanning electron microscopy and attenuated total reflectance-Fourier transform infrared spectroscopy, respectively. The surface wettability of the proposed MMM films was measured by water contact angle analysis and its porosity was studied by N2 adsorption/desorption analysis. To attain optimal microextraction performance, optimization of both thin film composition and microextraction procedure was conducted, followed by a thorough evaluation of figures of merit under the optimized conditions. The limits of detection and quantitation were determined to be 1.5 and 5 µg L−1 for both E2 and E1. The linear dynamic range for both compounds was from 5 to 150 µg L−1. The method's repeatability was investigated on a single film for 6 extractions, as well as on 3 different films and the relative standard deviation values were 4.43 and 4.91 for E2 and 5.36 and 6.03 for E1, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • cMOF/LDH hetero-nano petals decorated with Metal-N sites shelled over WNO nanowire show superior bifunctional activity. • RuCoFe-NPs@WNO-NWs exhibits outstanding catalytic performance in OER (230 mV @ 10 mAcm−2) and HER (49 mV @ 10 mAcm−2) in alkaline medium. • RuCoFe-NPs@WNO-NWs needing only 1.49 V for an alkaline solution and 1.55 V for seawater. • Designed electrocatalyst holds promise for practical water-splitting applications. • Numerous exposed edges of WNO nanowires and active center sites within the formed cMOF/LDHs heterostructure contribute to the enhanced electrocatalytic activity. Addressing the challenges of enhancing water-splitting efficiency necessitates the exploration and rational design of high-performance and durable electrocatalysts with appealing nanoarchitectures. In this study, we present the design and fabrication of conjugated cMOF/LDH hetero-nano petals decorated with monodispersed Metal-N sites, which are uniformly shelled over tungsten oxynitride (WNO) nanowire arrays to form a unique core–shell architecture. For this rational engineering, WNO nanowire arrays were grown on carbon cloth. Then, a thin-layered Ru-Co-Fe layered double hydroxide (RuCoFe/LDH) was deposited around these wires, resulting in a highly porous three-dimensional array of hierarchical hetero RuCoFe-LDHs@WNO-NWs core–shell nanowires (RuCoFe-NSs@WNO-NWs). Subsequently, the linkers coordinated with the RuCoFe-LDH nanosheets and transformed them in-situ into the RuCoFe-cMOF nano petals (RuCoFe-NPs@WNO-NWs). Notably, the linker's amino groups functioned as hooks for precisely anchoring and stabilizing metal sites, forming the metal nitride (M-N) moieties. Interestingly, the designed bi-functional catalyst exhibited superior catalytic activities for both OER (230 mV @ 10 mAcm−2) and HER (49 mV @ 10 mAcm−2) in an alkaline medium. Additionally, an electrolyzer cell employing Ru-CoFe-NPs@WNO-NWs as a bi-functional electrocatalyst required 1.49V to reach a current density of 10 mA cm−2. These remarkable catalytic performances can be attributed to several key factors, including opulent exposed active sites, an efficient charge/mass transport pathway, an optimized electronic structure, and an interfacial synergy effect. Hence, this study provides a new perspective for the design of efficient bi-functional electrocatalysts for use in the energy related electrochemical devices. [ABSTRACT FROM AUTHOR]

A metal complex (R-TAP-Pd(II)) constructed by chiral molecule R-TAP coordinated Pd(II) was used to modify g-C 3 N 4 to promote the separation efficiency of photogenerated carriers. Meanwhile, the R-TAP-Pd(II) acts as an activation site for proton reduction reaction, which enhances the photocatalytic H 2 evolution. [Display omitted] The photocatalytic H 2 production activity of polymer carbon nitride (g-C 3 N 4) is limited by the rapid recombination of photoelectron-hole pairs and slow surface reduction dynamic process. Here, a supramolecular complex (named R-TAP-Pd(II)) was fabricated via self-assembly of (R)-N-(1-phenylethyl)-4-(4-(pyridin-2-yl)-1H-1,2,3-triazol-1-yl)benzamide (R-TAP) with Pd(II) and used to modify g-C 3 N 4. In the R-TAP-Pd(II)@g-C 3 N 4 composite photocatalyst, the spin polarization of R-TAP-Pd(II) can promote charge transfer and inhibit photogenerated carrier recombination, as confirmed by spectral tests and photoelectrochemical performance tests. Electrochemical tests and in situ X-ray photoelectron spectroscopy (XPS) tests proved that the Pd(II) ion in the R-TAP-Pd(II) molecule can serve as active sites to accelerate H 2 production. The R-TAP-Pd(II)@g-C 3 N 4 presented a photocatalytic H 2 generation rate of 1085 μmol g−1 h−1 when exposed to visible light, which was a about 278-fold increase compared with g-C 3 N 4. This work finds a new approach to boost the photocatalytic efficiency of g-C 3 N 4 via supramolecular self-assembly. [ABSTRACT FROM AUTHOR]

A two-dimensional porous g-C 3 N 4 /MXene heterostructure (CN-MX) with intrinsic defects was designed as the desolvation promoter to accelerate the dissociation of solvated Li+ and propel the sulfur redox conversion. The Li-S cells with g-C 3 N 4 /MXene heterostructure demonstrated satisfactory areal capacity (5.5 mAh cm−2 at 0.2 C) and impressive low-temperature performance at 0 °C (91.6% capacity retention after 100 cycles at 0.5 C). [Display omitted] Lithium-sulfur (Li-S) batteries exhibit superior theoretical capacity and energy density but are still hindered by the sluggish redox conversion kinetic of lithium polysulfides arising from the significant desolvation barrier, especially under high current density or low-temperature environments. Herein, a two-dimensional (2D) porous graphitic phase carbon nitride/MXene (CN-MX) heterostructure with intrinsic defects was designed via electrostatic adherence and in-situ thermal polycondensation. In the design, the defect-rich CN with abundant catalytic activity and porous structure could efficiently facilitate the lithium polysulfides capture, the dissociation of solvated lithium-ion (Li+), and fast Li+ diffusion. Concurrently, 2D MXene nanosheets with high electronic conductivity could act as charge transport channels and provide electrochemical active sites for sulfur redox reactions. The Li-S cells with CN-MX heterostructure modified separator demonstrated uncommon rate performance (945 mAh/g at 4.0 C) and satisfactory areal capacity (5.5 mAh cm−2 at 0.2 C). Most remarkably, even at 0 °C, the assembled Li-S batteries performed favorable cycle stability (91.6% capacity retention after 100 cycles at 0.5 C) and outstanding rate performance (695 mAh/g at 2.0 C), and superior high loading performance (5.1 mAh cm−2 at 0.1 C). This work offers exciting new insights to enable Li-S batteries to operate in extreme environments. [ABSTRACT FROM AUTHOR]

High-entropy ceramics have gained increasing interest due to unique properties unattainable by traditional materials. Though a large number of high-entropy ceramics have emerged, there was still in lack of theoretical predictions of phase composition on multicomponent solid solutions, which was probably caused by the composition complexity. In this work, employing Thermo-Calc and TCHEA4 database, a series of equilibrium phase data was generated from quaternary solid solution nitrides formed by the five elements of Ti, V, Cr, Zr, and N, while five quaternary solid solution nitrides with various nitrogen stoichiometry were prepared by SPS utilizing commercially available transition metal and their nitrides at 1600 °C. The detection of phase composition during the experiment and thermodynamic calculation confirmed that an increase in nitrogen content was beneficial for the formation of a single-phase solid solution. Due to the variation of nitrogen stoichiometry, the concentrations of nitrogen-metal bonds changed accordingly, resulting in different relative densities and mechanical properties. On the basis of the experimental data, CALPHAD, with a maximum absolute error of only 8.31 %, was established, providing a powerful tool for predicting phase in the complex composition-temperature space of compositionally complex ceramics. [ABSTRACT FROM AUTHOR]

Antibiotic residues have become a significant challenge in food safety, threatening both ecosystem integrity and human health. To combat this problem, we developed an innovative photo‐powered, self‐powered aptasensor that employs a novel carbon‐doped three‐dimensional graphitic carbon nitride (3D‐CN) combined with a metal‐organic framework composed of N‐doped copper(I) oxide‐carbon (Cu2O@C) skeletons. The 3D‐CN serves as the photoanode, offering stable photocurrent production due to its three‐dimensional open framework structure. The N‐doped Cu2O@C acts as the photocathode, providing oxidation protection for the metal core and enhancing light absorption due to its metal‐organic framework structure. A key feature of our work is exploiting the Fermi level difference between the n‐type photoanode and p‐type photocathode, which facilitates faster migration of photogenerated electrons toward the photocathode, thereby enhancing the sensor's self‐powered effect. Experimental results reveal that upon aptamer loading, the sensor can linearly detect tetracycline (TC) within a range of 0.5 pmol/L to 300 nmol/L, with a detection limit as low as 0.13 pmol/L. It also demonstrates excellent selectivity, stability, and reproducibility, making it applicable to real samples such as milk and river water. Consequently, our research provides a highly efficient and sensitive method for monitoring TC in food, with significant practical implications and profound impacts on food safety. [ABSTRACT FROM AUTHOR]

The present study examined potential benefits of heteroatom doping to manipulate the electrical structure and to enhance the efficiency of the sensor, with an emphasis on developing inexpensive, metal‐free electrochemical sensors. Melamine and ammonium oxalate were used as precursors in a one‐step thermal polymerization technique yielding oxygen‐doped graphitic carbon nitride (O‐gCN). Following synthesis, the material's structural and morphological properties were thoroughly examined using a multitude of analytical techniques, including EIS. A notable decrease in impedance was observed, suggesting improved conductivity. Additionally, the doping approach exhibited a noticeable improvement in reduction current receptivity and surface area as compared to unmodified graphitic carbon nitride (g‐CN). Utilizing both differential pulse voltammetry (DPV) and the classical cyclic voltammetry (CV) methods, we investigated the electro oxidation of uric acid (UA) as well as concentration dependence and selectivity studies using oxygen‐doped graphitic carbon nitride modified glassy carbon electrode (O‐gCN@GCE). O‐gCN@GCE demonstrated remarkable performance, allowing the detection of UA concentrations as low as 7.784 µAµM−1cm−2. Its low detection limit of 0.57 µM and wider linear range (5–120 µM) further highlighted its potential for extremely sensitive assays and its remarkable capacity to operate over a broad UA concentration range. [ABSTRACT FROM AUTHOR]

One of the most fascinating 2D nanomaterials (NMs) ever found is various members of MXene family. Among them, the titanium‐based MXenes, with more than 70% of publication‐related investigations, are comparatively well studied, producing fundamental foundation for the 2D MXene family members with flexible properties, familiar with a variety of advanced novel technological applications. Nonetheless, there are still more candidates among transitional metals (TMs) that can function as MXene NMs in ways that go well beyond those that are now recognized. Systematized details of the preparations, characteristics, limitations, significant discoveries, and uses of the novel M‐based MXenes (M‐MXenes), where M stands for non‐Ti TMs (M = Sc, V, Cr, Y, Zr, Nb, Mo, Hf, Ta, W, and Lu), are given. The exceptional qualities of the 2D non‐Ti MXene outperform standard Ti‐MXene in several applications. There is many advancement in top‐down as well as bottom‐up production of MXenes family members, which allows for exact control of the M‐characteristics MXene NMs to contain cutting‐edge applications. This study offers a systematic evaluation of existing research, covering everything in producing complex M‐MXenes from primary limitations to the characterization and selection of their applications in accordance with their novel features. The development of double metal combinations, extension of additional metal candidates beyond group‐(III–VI)B family, and subsequent development of the 2D TM carbide/TMs nitride/TM carbonitrides to 2D metal boride family are also included in this overview. The possibilities and further recommendations for the way of non‐Ti MXene NMs are in the synthesis of NMs will discuss in detail in this critical evaluation. [ABSTRACT FROM AUTHOR]

The material properties of precipitated iron promoted with either K, Mn, Pt, Ru, Zn, respectively, and their catalytic performance in the Fischer‐Tropsch synthesis were evaluated. A special attention was paid to the influence of ammonia on the reaction. Different spectroscopic methods e. g. XPS and XANES revealed the structure of both iron and the corresponding promoter. Conclusions were also drawn for the activated (reduced) catalysts. Applying temperature programmed reduction and XRD, the presence of iron nitrides through ammonia treatment was discovered. In the presence of ammonia under the Fischer‐Tropsch reaction conditions the formation of amines was detected. The highest yield of amines was observed for the manganese promoted catalyst. The investigation of hydrogen activating and not activating promoters in combination with iron, made it possible to hypothesise about the mechanism of the incorporation of ammonia into hydrocarbons under Fischer‐Tropsch reaction conditions. [ABSTRACT FROM AUTHOR]

For the 2D metal‐free carbon catalysts, the atomic coplanar architecture enables a large number of pz orbitals to overlap laterally, thus forming π‐electron delocalization, and the delocalization degree of the central atom dominates the catalytic activity. Herein, designing sulfur‐doped defect‐rich graphitic carbon nitride (S‐Nv‐C3N4) materials as a model, we propose a strategy to promote localized electron polarization by enhancing the ferromagnetism of ultra‐thin 2D carbon nitride nanosheets. The introduction of sulfur (S) further promotes localized ferromagnetic coupling, thereby inducing long‐range ferromagnetic ordering and accelerating the electron interface transport. Meanwhile, the hybridization of sulfur atoms breaks the symmetry and integrity of the unit structure, promotes electron enrichment and stimulating electron delocalization at the active site. This optimization enhances the *OOH desorption, providing a favorable kinetic pathway for the production of hydrogen peroxide (H2O2). Consequently, S‐Nv‐C3N4 exhibits high selectivity (>95 %) and achieves a superb H2O2 production rate, approaching 4374.8 ppm during continuous electrolysis over 300 hour. According to theoretical calculation and in situ spectroscopy, the ortho‐S configuration can provide ferromagnetic perturbation in carbon active centers, leading to the electron delocalization, which optimizes the OOH* adsorption during the catalytic process. [ABSTRACT FROM AUTHOR]

Solar‐driven synthesis of hydrogen peroxide (H2O2) through photocatalysis stands out as a promising avenue for sustainable energy generation, marked by environmental friendliness and industrial feasibility. However, the inherent limitations of carbon nitride (CN) in photocatalytic H2O2 production significantly impede their performance. Herein, a novel 0D/2D carbon dots‐modified CN nanosheet heterojunction (CDsMCN) is introduced, synthesized through a hydrothermal‐calcination tandem strategy induced by CDs derived from melamine. This innovative technique enhances the n→π* electronic transition in CDsMCN, accelerating the separation efficiency of electron‐hole pairs, boosting oxygen adsorption, and promoting a highly selective 2e− ORR. Comparative to pristine CN, CDs10MCN exhibited a remarkable tenfold increase in H2O2 production, reaching an impressive 1.48 mmol L−1. Furthermore, CDs10MCN demonstrates exceptional stability, maintaining its catalytic efficiency at the initial level over four consecutive cycles. The notable achievement of a molar selectivity of H2O2 ≈80% at an onset potential of 0.6 V (vs RHE) underscores its exceptional ability to produce the desired product selectively. Advanced in situ characterization together with DFT calculations revealed that the ultrathin CDs10MCN nanosheet heterojunction with enhanced n→π* electronic transition improves its optical properties, reduces bandgap, facilitates fast charge migration, and increases photocatalytic H2O2 performance, thereby serving as a promising candidate for advanced catalytic applications. [ABSTRACT FROM AUTHOR]

The use of ultrasound in the presence of semiconductor materials is considered a novel technique for the degradation of hazardous organic pollutants in water. In this study, graphitic carbon nitride (g), graphene oxide (GO), and Cobalt ferrite, CoFe 2 O 4 (CF) nanoparticles were synthesized via soft-template-assisted synthesis, Hummer's, and hydrothermal methods, respectively. Subsequently, the hybrid magnetic g-C 3 N 4 /CoFe 2 O 4 /GO (g-CF1@GO, g-CF2@GO, g-CF3@GO, and g-CF4@GO) nanocomposites were prepared via a simple hydrothermal route at 180 °C. The crystallite structure, functional groups, morphology, and energy band gaps were characterized by XRD diffraction, FT-IR, TEM, and UV–vis DRS. The heterostructure nanocomposites were formed, as evidenced by the TEM data, with an average crystallite size of 13.4 nm and band gap energies of 2.19–1.80 eV, suggesting their suitability for sono/photo degradation processes. Pyrene, a tetracyclic polycyclic aromatic hydrocarbon (PAH) was chosen as a model pollutant to evaluate the performance of the prepared nanocomposites toward sonocatalytic degradation. The nanocomposites exhibited higher degradation performances than individual materials. The sonocatalytic degradation of pyrene revealed that the g-CF4@GO nanocomposite exhibited the highest sonocatalytic activity and achieved 86.7 and 92.3 % degradation efficiency for 10 and 5 mg/L of pyrene under ultrasonic irradiation (40 mg/L, 50 W and 20 kHz) in 120 min. In addition, the sonocatalytic degradation of pyrene is performed in the absence of any oxidant and follows a pseudo-first-order kinetics. Trapping experiments were carried out to investigate the sonocatalytic degradation mechanism, and the results showed that ●O 2 − was the major reactive species. The easily recoverable magnetic nanocomposite via a simple magnet was tested for its recyclability and reusability, and it was observed that it could degrade up to 78 % of pyrene in four cycles. [ABSTRACT FROM AUTHOR]

We demonstrated a nonenzymatic electrochemical sensor based upon vanadium-doped nickel oxide composite with graphitic carbon nitride. The g-C 3 N 4 was prepared by annealing Urea at 550 °C for 3 h in a muffle furnace. The nanocomposite was synthesized using a microwave-assisted method, followed by thermal annealing at different temperatures. The successful formation of V–NiO/g-C 3 N 4 was confirmed by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy. SEM images show the layered sheets with porous structure, which depends on annealing temperature; as we increase the temperature, the porosity increases. Afterwards, the electrochemical sensing properties were verified by CV, LSV, DPV, and amperometric studies in 0.2 M KOH in the presence of Ascorbic acid and Dopamine. The experimental results show that our prepared sample has excellent electrochemical biosensing abilities towards AA and DA with LOD 1.16 μM and 0.16 μM, respectively. It also offers good selectivity, exceptional reproducibility, and long-term stability owing to the combined effect of NiO and g-C 3 N 4. Finally, the electrochemical sensing of H 2 O 2 was detected in the same environment by conducting CV and amperometric studies. Our modified electrode has proven its noble ability to sense H 2 O 2 with excellent repeatability, stability and low LOD 0.2 μM with a wide linear working range (0.5 mM–4 mM). It has the potential to be used for multi-molecule selection biosensing with excellent selectivity and sensitivity. [Display omitted] [ABSTRACT FROM AUTHOR]

With increasingly serious environmental pollution problems, the development of efficient photocatalytic materials has become a hotspot in current research. This study focused on phosphorus-doped carbon nitride/titanium dioxide (PCT) Z-type heterojunctions, aiming to deeply investigate their photocatalytic degradation and photosensitive antimicrobial properties. A PCT Z-type heterojunction was successfully fabricated using melamine phosphate, cyanuric acid, and titanium dioxide. The structure, morphology, and optical properties of PCT Z-type heterojunctions were explored by FTIR, XRD, XPS, BET, SEM, UV-Vis DRS, TEM, EIS, and PL. A comprehensive and in-depth analysis of the structure, morphology, and optical properties of PCT Z-type heterojunctions was carried out. The photocatalytic degradation experiments revealed that PC3T Z-type heterojunctions exhibited an excellent degradation capability for methylene blue (MB) under visible light. The effect of PC3T on the adsorption–photocatalytic degradation of MB is more than 1.5 times that of a single titanium dioxide and P-doped carbon nitride. In the photosensitive antimicrobial performance study, PC3T reduced the survival rate of E. coli to 7%, after 120 min. Through free radical trapping experiments, it was shown that the hydroxyl radicals and superoxide radicals exerted an influence on the photocatalytic process. This study offers new ideas and approaches to address environmental pollution problems and holds significant theoretical and applied value. [ABSTRACT FROM AUTHOR]

This paper presents a comparison of two-component ammonia-based inlet atmospheres diluted with either hydrogen (NH3/H2) or nitrogen (NH3/N2). Taking advantage of the features of inlet atmospheres diluted with nitrogen and hydrogen, four two-stage processes were designed and carried out, which were juxtaposed with two single-stage processes carried out only in an NH3 atmosphere. A common parameter of the processes carried out was the same value of nitrogen availability in each process stage. The gas nitriding process was carried out on ASIS 1085 non-alloy steel and ASIS 52100 alloy steel. It was found that the chemical composition of the steels studied, for the adopted nitriding process parameters, did not affect the kinetics of the growth in the mass of nitrided samples as a function of the nitriding time. However, the additions of alloying elements present in the steels studied significantly affected the nitrogen distribution between the resulting iron nitride layer and the diffusion zone in the nitrided substrate. Because of the presence of chromium in AISI 52100 steel, a larger mass of nitrogen accumulated in the nitriding zone in the solution compared with unalloyed AISI 1085 steel. As a result, with the same increase in the mass of nitrided steel, a thicker layer of iron nitrides formed on AISI 1085 steel than on AISI 52100 steel. [ABSTRACT FROM AUTHOR]

Metal polynitrides have raised significant interest for their applications as potential high‐energy‐density materials (HEDMs). Despite extensive research on energetic polynitrogen species, reducing synthesis pressures and realizing their recovery at ambient conditions remain challenging. Here, for the first time, the zigzag N4 chains are successfully stabilized in the new polynitride Ce2N6 and recovered to ambient pressure and temperature by introducing cerium nitride as a precursor. The stable mechanism of the recoverable N4 chain originates from the large quantity of charge captured, the favorable bonding environment, and low structural enthalpy. This study reveals the crucial role of precursors in stabilizing and recovering polynitrogen species, providing an alternative route to design and prepare novel HEDMs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dual-metal cocatalysts consisting of Pt NCs and In NPs were anchored on CN matrix. • The optimal Pt-In/CN exhibited an impressive photocatalytic H 2 production activity. • Pt NCs and In NPs as traps boosted the separation and migration of photogenerated charges. • Bimetallic cocatalysts regulated optimal adsorption behavior of H* intermediates for fast kinetics. Photocatalytic H 2 production is envisioned as a promising pillar of sustainable energy conversion system to address the energy crisis and environmental issues but still challenging. Herein, a strategy is proposed to design a dual-metal cocatalysts consisting of Pt nanoclusters (Pt NCs) and In nanoparticles (In NPs) anchored on polymeric carbon nitride (Pt-In/CN) for boosting photocatalytic water splitting. As expected, the designed Pt-In/CN photocatalyst exhibits an impressive H 2 production rate of 6.49 mmol·h−1·g−1 with an apparent quantum yield (AQY) of 33.56 % at 400 nm, which is 2.8- and 11.2-fold higher than those of the Pt/CN and In/CN, respectively. Combining experimental characterization with theoretical calculation demonstrates the synergistic mechanisms underpinning the enhanced photocatalytic activity. The Pt NCs and In NPs serve as photogenerated electron and hole trapping sites, respectively, which achieves the spatial separation of charge carriers and induces the polarized surface charge distribution, thus fostering optimal adsorption behavior of intermediates. More importantly, the p-block In NPs modulate the electronic microenvironment of Pt NCs to attenuate the adsorption behavior of H* intermediates for accelerated H 2 evolution kinetics. This work unveils a versatile strategy to regulate the electronic structures of dual-metal sites with synergy by establishing charge transfer mechanism for dual-metal cocatalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] The challenge of mitigating pollution stemming from industrial exhaust emissions is a pressing issue in both academia and industry. This study presents the successful synthesis of nitrogen-defect-enriched graphite carbon nitride (g-C 3 N 4) using a two-step calcination technique. Furthermore, a g-C 3 N 4 -Au heterostructure was fabricated through the photo-deposited Au quantum dots (QDs). When subjected to visible light irradiation, this heterostructure exhibited robust nitric oxide (NO) photooxidation activity and stability. With its fluffy, porous structure and large surface area, the nitrogen-defect-enriched g-C 3 N 4 provides more active sites for photooxidation processes. The ability of g-C 3 N 4 to absorb visible light is enhanced by the local surface plasmon resonance (LSPR) effect of Au QDs. Additionally, the lifetime of photogenerated charge carriers is extended by the presence of N defects and Au, which effectively prevent photogenerated electron-hole pairs from recombining during the photooxidation process. Moreover, the oxidation pathway of NO was analyzed through In-situ Fourier transform infrared (FT-IR) spectroscopy and Density Functional Theory (DFT) calculation. Computational findings revealed that the introduction of Au QDs decreases the activation energy of the oxidation reaction, thereby facilitating its occurrence while diminishing the formation of intermediate products. As a result, NO is predominantly converted to nitrate (NO 3 −). This work unveils a novel approach to constructing semiconductor-cocatalyst heterostructures and elucidates their role in NO photooxidation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Newly synthesized Cu 3 N catalyst was employed for electrocatalytic nitrate reduction and ammonia production. • The strategy of balancing *H 2 O and *NO 3 intermediates adsorption for enhanced NO 3 RR was highlighted. • In-situ and ex-situ analysis verify the potential driven reconstruction and rehabilitation of Cu 3 N. Nitrate in surface and underground water caused systematic risk to the ecological environment. The electrochemically reduction of nitrate into ammonia (NO 3 RR), offering a sustainable route for nitrate containing wastewater treatment and ammonia fertilizer conversion. Exploration of catalyst with improved catalytic activity with lower energy barriers is still challenging. Here, we report a copper nitride (Cu 3 N) catalyst with moderate *NO x and *H 2 O intermediates adsorptions showed enhanced NO 3 RR performance. Density functional theory calculations reveals that the unique electronic structure of Cu 3 N provides efficient active sites for NO 3 RR, thus enabled balanced adsorption of *NO 3 and *H 2 O (ΔE descriptor), sufficient active hydrogen, and moderate intermediate (*NO 3 → HNO 3 , *NH 2 →*NH 3) adsorption energy. Notably, the in-situ analysis technology revealed potential-driven reconstruction and rehabilitation of Cu 3 N, forming possible nitrogen vacancy, thus implied for better mechanism understanding. The NO 3 RR activity of Cu 3 N surpasses that of most recent catalysts and demonstrates superior stability and implies the application for NH 4 + fertilizer recovery, which maintaining an NH 3 Faradaic efficiency of 93.1 % and high yield rate of 2.9 mg cm2h−1 at −0.6 V versus RHE. These findings broaden the application scenarios of Cu 3 N catalyst for ammonia synthesis and provide strategy on improving NO 3 RR performance. [ABSTRACT FROM AUTHOR]

[Display omitted] In this study, a directional loading of cadmium sulfide (CdS) nanoparticles (NPs) was achieved on the opposite edges of nickel metal–organic framework (Ni-MOF) nanosheets (NSs) by adjusting the weight ratio of CdS NPs in the reaction process to produce effective visible light photocatalysts. The close contact between the zero-dimensional (0D) and two-dimensional (2D) regions and the matching positions of the bands promoted charge separation and heterojunction formation. The optimal CdS NPs loading of composite material was 40 wt%. At this ratio, CdS NPs grew primarily at the opposite edges of the Ni-MOF NSs rather than on their surfaces. When lactic acid was used as the sacrificial agent, the hydrogen production rate of the 40 %-CdS/Ni-MOF heterojunction under visible light irradiation was 19.6 mmol h−1 g−1, making a 20-fold enhancement compared to the original CdS NPs sample (1.0 mmol h−1 g−1). The charge carriers generated in CdS NPs were transferred to Ni-MOF NSs through heterojunctions, where Ni-MOF NSs also served as cocatalysts to improve hydrogen production. The combination of the two materials improved the light absorption ability. In particular, the 40 %-CdS/Ni-MOF heterojunction exhibited good photostability, effectively preventing the photocorrosion of CdS NPs. This study introduces an approach for constructing efficient and stable photocatalysts for visible light–driven photocatalytic hydrogen production. [ABSTRACT FROM AUTHOR]

By embedding Na ions into graphitic carbon nitride, the directional migration of photo-generated electrons towards Na sites is achieved, thereby creating additional reaction sites. Moreover, the electron-rich Na sites enhance the adsorption and activation of CO 2. Consequently, the photocatalytic performance is improved to some extent. [Display omitted] The depressed directional separation of photogenerated carriers and weak CO 2 adsorption/activation activity are the main factors hampering the development of artificial photosynthesis. Herein, Na ions are embedded in graphitic carbon nitride (g-C 3 N 4) to achieve directional migration of the photogenerated electrons to Na sites, while the electron-rich Na sites enhance CO 2 adsorption and activation. Na/g-C 3 N 4 (NaCN) shows improved photocatalytic reduction activity of CO 2 to CO and CH 4 , and under simulated sunlight irradiation, the CO yield of NaCN synthesized by embedding Na at 550°C (NaCN-550) is 371.2 μmol g−1 h−1, which is 58.9 times more than that of the monomer g-C 3 N 4. By means of theoretical calculations and experiments including in situ fourier transform infrared spectroscopy, the mechanism is investigated. This strategy which improves carrier separation and reduces the energy barrier at the same time is important to the development of artificial photosynthesis. [ABSTRACT FROM AUTHOR]

Compositionally complex transitional metal nitrides are possible candidates for ultra‐high temperature usage and are known for their superior properties due to the high configuration entropy. It is often difficult to synthesize pure metal nitrides in bulk, due to significant oxygen contamination; hence, they are synthesized mainly as thin films through magnetron sputtering, chemical vapor deposition or surface nitridation of high entropy alloys. The present article reports on a single‐phase compositionally complex ceramic, i.e., (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)NxC1−x, that is synthesized for the first time by employing an organometallic precursor route and using a double ammonolysis process. A multidisciplinary approach is performed to study these compositionally complex nitride and carbonitride systems, including experimental and theoretical investigations. [ABSTRACT FROM AUTHOR]