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The synthesis of transition metal nitrides nanocrystals (TMNs NCs) has posed a significant challenge due to the limited reactivity of nitrogen sources at lower temperatures and the scarcity of available synthesis methods. In this study, we present a novel colloidal synthesis strategy for the fabrication of Cu3N nanorods (NRs). It is found that the trace oxygen (O2) plays an important role in the synthesis process. And a new mechanism for the formation of Cu3N is proposed. Subsequently, by employing secondary lateral epitaxial growth, the Cu3N-Cu2O heteronanostructures (HNs) can be prepared. The Cu3N NRs and Cu3N-Cu2O HNs were evaluated as precursor electrocatalysts for the CO2 reduction reaction (CO2RR). The Cu3N-Cu2O HNs demonstrate remarkable selectivity and stability with ethylene (C2H4) Faradaic efficiency (FE) up to 55.3%, surpassing that of Cu3N NRs. This study provides innovative insights into the reaction mechanism of colloidal synthesis of TMNs NCs and presents alternative options for designing cost-effective electrocatalysts to achieve carbon neutrality.

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Nitrate in surface and underground water caused systematic risk to the ecological environment. The electrochemically reduction of nitrate into ammonia (NO3RR), 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 (Cu3N) catalyst with moderate *NOx and *H2O intermediates adsorptions showed enhanced NO3RR performance. Density functional theory calculations reveals that the unique electronic structure of Cu3N provides efficient active sites for NO3RR, thus enabled balanced adsorption of *NO3 and *H2O (ΔE descriptor), sufficient active hydrogen, and moderate intermediate (*NO3 â†’ HNO3, *NH2→*NH3) adsorption energy. Notably, the in-situ analysis technology revealed potential-driven reconstruction and rehabilitation of Cu3N, forming possible nitrogen vacancy, thus implied for better mechanism understanding. The NO3RR activity of Cu3N surpasses that of most recent catalysts and demonstrates superior stability and implies the application for NH4+ fertilizer recovery, which maintaining an NH3 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 Cu3N catalyst for ammonia synthesis and provide strategy on improving NO3RR performance.

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Enhancing the reaction selectivity for multicarbon products (C2+) is an important goal for the electrochemical CO(2) reduction (ECO(2)R) process. Cuprous compounds have demonstrated promising C2+ selectivity in the ECO(2)R process, but further investigation is necessary to thoroughly elucidate their catalytic behavior toward C2+ oxygenate production. In this study, copper nitride-based materials with varying reduction rates were employed as precatalysts. Consequently, a relationship between the selectivity toward C2+ oxygenates and the Cu oxidation state during the ECOR process is established. Results of theoretical and experimental analyses reveal that the Cu0/Cu+ interface plays a key role in enhancing *CO adsorption while lowering the formation energy of *CH2CO, thereby promoting acetate production. This work highlights the significance of the Cu0/Cu+ interface in the regulation of C2+ oxygenate production and paves the way for the development of highly selective catalysts in the future.

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This material can be considered to be an interesting eco-friendly choice to be used in the photovoltaic field. In this work, we present the fabrication of Cu3N thin films by reactive radio-frequency (RF) magnetron sputtering at room temperature, using nitrogen as the process gas. Different RF power values ranged from 25 to 200 W and gas pressures of 3.5 and 5 Pa were tested to determine their impact on the film properties. The morphology and structure were exhaustively examined by Atomic Force Microscopy (AFM), Fourier Transform Infrared (FTIR) and Raman Spectroscopies and X-ray Diffraction (XRD), respectively. The AFM micrographs revealed different morphologies depending on the total pressure used, and rougher surfaces when the films were deposited at the lowest pressure; whereas FTIR and Raman spectra exhibited the characteristics bands related to the Cu-N bonds of Cu3N. Such bands became narrower as the RF power increased. XRD patterns showed the (100) plane as the preferred orientation, that changed to (111) with the RF power, revealing a worsening in structural quality. Finally, the band gap energy was estimated from transmission spectra carried out with a Perkin Elmer 1050 spectrophotometer to evaluate the suitability of Cu3N as a light absorber. The values obtained demonstrated the capability of Cu3N for solar energy conversion applications, indicating a better film performance under the sputtering conditions 5.0 Pa and RF power values ranged from 50 to 100 W.

RESUMEN

Cu3N has been grown on m-Al2O3 by aerosol-assisted chemical vapor deposition using 0.1 M CuCl2 in CH3CH2OH under an excess of NH3 at 600 °C, which led to the deposition of Cu that was subsequently converted into Cu3N under NH3: O2 at 400 °C in a two-step process without exposure to the ambient. The reaction of CuCl2 with an excess of NH3 did not lead to the growth of Cu3N, which is different to the case of halide vapor phase epitaxy of III-V semiconductors. The Cu3N layers obtained in this way had an anti-ReO3 cubic crystal structure with a lattice constant of 3.8 Å and were found to be persistently n-type, with a room temperature carrier density of n = 2 × 1016 cm-3 and mobility of µn = 32 cm2/Vs. The surface depletion, calculated in the effective mass approximation, was found to extend over ~0.15 µm by considering a surface barrier height of ϕB = 0.4 eV related to the formation of native Cu2O.

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Copper nitride, a metastable semiconductor material with high stability at room temperature, is attracting considerable attention as a potential next-generation earth-abundant thin-film solar absorber. Moreover, its non-toxicity makes it an interesting eco-friendly material. In this work, copper nitride films were fabricated using reactive radio frequency (RF) magnetron sputtering at room temperature, 50 W of RF power, and partial nitrogen pressures of 0.8 and 1.0 on glass and silicon substrates. The role of argon in both the microstructure and the optoelectronic properties of the films was investigated with the aim of achieving a low-cost absorber material with suitable properties to replace the conventional silicon in solar cells. The results showed a change in the preferential orientation from (100) to (111) planes when argon was introduced in the sputtering process. Additionally, no structural changes were observed in the films deposited in a pure nitrogen environment. Fourier transform infrared (FTIR) spectroscopy measurements confirmed the presence of Cu-N bonds, regardless of the gas environment used, and XPS indicated that the material was mainly N-rich. Finally, optical properties such as band gap energy and refractive index were assessed to establish the capability of this material as a solar absorber. The direct and indirect band gap energies were evaluated and found to be in the range of 1.70-1.90 eV and 1.05-1.65 eV, respectively, highlighting a slight blue shift when the films were deposited in the mixed gaseous environment as the total pressure increased.

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High Power Impulse Magnetron Sputtering (HiPIMS) has generated a great deal of interest by offering significant advantages such as high target ionization rate, high plasma density, and the smooth surface of the sputtered films. This study discusses the deposition of copper nitride thin films via HiPIMS at different deposition pressures and then examines the impact of the deposition pressure on the structural and electrical properties of Cu3N films. At low deposition pressure, Cu-rich Cu3N films were obtained, which results in the n-type semiconductor behavior of the films. When the deposition pressure is increased to above 15 mtorr, Cu3N phase forms, leading to a change in the conductivity type of the film from n-type to p-type. According to our analysis, the Cu3N film deposited at 15 mtorr shows p-type conduction with the lowest resistivity of 0.024 Ω·cm and the highest carrier concentration of 1.43 × 1020 cm-3. Furthermore, compared to the properties of Cu3N films deposited via conventional direct current magnetron sputtering (DCMS), the films deposited via HiPIMS show better conductivity due to the higher ionization rate of HiPIMS. These results enhance the potential of Cu3N films' use in smart futuristic devices such as photodetection, photovoltaic absorbers, lithium-ion batteries, etc.

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The precursor conversion chemistry and surface chemistry of Cu3 N and Cu3 PdN nanocrystals are unknown or contested. Here, we first obtain phase-pure, colloidally stable nanocubes. Second, we elucidate the pathway by which copper(II) nitrate and oleylamine form Cu3 N. We find that oleylamine is both a reductant and a nitrogen source. Oleylamine is oxidized by nitrate to a primary aldimine, which reacts further with excess oleylamine to a secondary aldimine, eliminating ammonia. Ammonia reacts with CuI to form Cu3 N. Third, we investigated the surface chemistry and find a mixed ligand shell of aliphatic amines and carboxylates (formed in situ). While the carboxylates appear tightly bound, the amines are easily desorbed from the surface. Finally, we show that doping with palladium decreases the band gap and the material becomes semi-metallic. These results bring insight into the chemistry of metal nitrides and might help the development of other metal nitride nanocrystals.

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The search for ultrafast and simple methods to fabricate non-noble metal catalysts to boost electrocatalytic oxygen reduction reaction (ORR) is still ongoing. Herein, we demonstrate a one-step microwave-assisted heating method to prepare copper nitride/iron/iron carbide nanoparticle hybrids (CuNC/Fe/Fe3C/CNT). This ultrafast heating method induces plentiful carbon-wrapped metal and Fe3C nanoparticles that are attached to the surface of CNT and scattered nanosheets. The CuNC/Fe/Fe3C/CNT exhibit a half-wave potential (E1/2) of 0.886 V toward the ORR in alkaline solution, with 220 mV more positive E1/2 than that of CuNC/CNT and Fe/Fe3C/CNT respectively. The activity of as-prepared catalysts is discussed by investigating their structures and compositions and their relationship with the ORR performance. Detailed analysis results disclose that the high activity of the CuNC/Fe/Fe3C/CNT catalysts could be attributed to the interaction of CuNC and Fe/Fe3C species. To be specific, as the electron donor, Fe/Fe3C nanoparticles induce electron localization and promote the formation of Cu (δ + )-NC (0 < Î´ < 2), therefore leading to the improvement of the ORR performance. This work may offer an ultrafast way to construct efficient catalysts with enhanced ORR performance.

Asunto(s)

RESUMEN

Electrochemical CO2 reduction to produce valuable C2 products is attractive but still suffers with relatively poor selectivity and stability at high current densities, mainly due to the low efficiency in the coupling of two *CO intermediates. Herein, it is demonstrated that high-density nitrogen vacancies formed on cubic copper nitrite (Cu3 Nx ) feature as efficient electrocatalytic centers for CO-CO coupling to form the key OCCO* intermediate toward C2 products. Cu3 Nx with different nitrogen densities are fabricated by an electrochemical lithium tuning strategy, and density functional theory calculations indicate that the adsorption energies of CO* and the energy barriers of forming key C2 intermediates are strongly correlated with nitrogen vacancy density. The Cu3 Nx catalyst with abundant nitrogen vacancies presents one of the highest Faradaic efficiencies toward C2 products of 81.7 ± 2.3% at -1.15 V versus reversible hydrogen electrode (without ohmic correction), corresponding to the partial current density for C2 production as -307 ± 9 mA cm-2 . An outstanding electrochemical stability is also demonstrated at high current densities, substantially exceeding CuOx catalysts with oxygen vacancies. The work suggests an attractive approach to create stable anion vacancies as catalytic centers toward multicarbon products in electrochemical CO2 reduction.

RESUMEN

Herein we describe an alternative strategy to achieve the preparation of nanoscale Cu3N. Copper(II) oxide/hydroxide nanopowder precursors were successfully fabricated by solution methods. Ammonolysis of the oxidic precursors can be achieved essentially pseudomorphically to produce either unsupported or supported nanoparticles of the nitride. Hence, Cu3N particles with diverse morphologies were synthesized from oxygen-containing precursors in two-step processes combining solvothermal and solid-gas ammonolysis stages. The single-phase hydroxochloride precursor, Cu2(OH)3Cl was prepared by solution-state synthesis from CuCl2·2H2O and urea, crystallising with the atacamite structure. Alternative precursors, CuO and Cu(OH)2, were obtained after subsequent treatment of Cu2(OH)3Cl with NaOH solution. Cu3N, in the form of micro- and nanorods, was the sole product formed from ammonolysis using either CuO or Cu(OH)2. Conversely, the ammonolysis of dicopper trihydroxide chloride resulted in two-phase mixtures of Cu3N and the monoamine, Cu(NH3)Cl under similar experimental conditions. Importantly, this pathway is applicable to afford composite materials by incorporating substrates or matrices that are resistant to ammoniation at relatively low temperatures (ca. 300 °C). We present preliminary evidence that Cu3N/SiO2 nanocomposites (up to ca. 5 wt.% Cu3N supported on SiO2) could be prepared from CuCl2·2H2O and urea starting materials following similar reaction steps. Evidence suggests that in this case Cu3N nanoparticles are confined within the porous SiO2 matrix.

RESUMEN

Copper nitride shows various properties that depend on the structure of the material and is influenced by the change in technical parameters. In the present work, Cu-N layers were synthesized using the pulsed magnetron sputtering method. The synthesis was performed under different operating conditions: direct current (DC) or alternating current (AC) power supply, and various atmospheres: pure Ar and a mixture of Ar + N2. The structural properties of the deposited layers were characterized by X-ray diffraction measurements, and Raman spectroscopy and scanning electron microscopy have been performed. Optical properties were also evaluated. The obtained layers showed tightly packed columnar grain features. The kinetics of the layer growth in the AC mode was lower than that observed in the DC mode, and the layers were thinner and more fine-grained. The copper nitride layers were characterized by the one-phase and two-phase polycrystalline structure of the Cu3N phase with the preferred growth orientation (100). The lattice constant oscillates between 3.808 and 3.815 Å for one-phase and has a value of 3.828 Å for a two-phase structure. Phase composition results were correlated with Raman spectroscopy measurements. Raman spectra exhibited a broad, diffused, and intense signal of Cu3N phase, with Raman shift located at 628-635 cm-1. Studies on optical properties showed that the energy gap ranged from 2.17 to 2.47 eV. The results showed that controlling technical parameters gives a possibility to optimize the structure and phase composition of deposited layers. The reported changes were discussed and attributed to the properties of the material layers and technology method.

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The practical implementation of the lithium metal anode is hindered by obstacles such as Li dendrite growth, large volume changes, and poor lifespan. Here, copper nitride nanowires (Cu3 N NWs) printed Li by a facile and low-cost roll-press method is reported, to operate in carbonate electrolytes for high-voltage cathode materials. Through one-step roll pressing, Cu3 N NWs can be conformally printed onto the Li metal surface, and form a Li3 N@Cu NWs layer on the Li metal. The Li3 N@Cu NWs layer can assist homogeneous Li-ion flux with the 3D channel structure, as well as the high Li-ion conductivity of the Li3 N. With those beneficial effects, the Li3 N@Cu NWs layer can guide Li to deposit into a dense and planar structure without Li-dendrite growth. Li metal with Li3 N@Cu NWs protection layer exhibits outstanding cycling performances even at a high current density of 5.0 mA cm-2 with low overpotentials in Li symmetric cells. Furthermore, the stable cyclability and improved rate capability can be realized in a full cell using LiCoO2 over 300 cycles. When decoupling the irreversible reactions of the cathode using Li4 Ti5 O12 , stable cycling performance over 1000 cycles can be achieved at a practical current density of ≈2 mA cm-2 .

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Oxide semiconductor thin-film transistors (TFTs) are currently used as the fundamental building blocks in commercial flat-panel displays because of the excellent performance of n-channel TFTs. However, except for a few materials, their p-channel performances have not been acceptable. Although some p-type oxide semiconductors exhibit superior hole transport properties, their TFT performances are greatly deteriorated, which is a major obstacle in the development of complementary metal-oxide-semiconductor (CMOS) circuits. Herein, an ionic nitride semiconductor, copper nitride (Cu3N), composed of environmentally benign elements is shown to exhibit highly symmetric hole and electron transport, indicating its suitability for application in CMOS circuits. We performed a two-step investigation. The first step was to examine the ultimate potential of Cu3N using an electric-double-layer transistor structure with epitaxial Cu3N channels measured at 220 K, which exhibited ambipolar operation with hole and electron mobilities of ∼5 and ∼10 cm2 V-1 s-1, respectively, and a high on/off ratio of ∼105. The second step is to demonstrate the feasibility of TFT circuits with a polycrystalline channel on non-single-crystal (SiO2/Si) substrates. CMOS-like inverters composed of two polycrystalline Cu3N ambipolar TFTs on a SiO2/Si substrate exhibited a high voltage gain of ∼100.

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The lack of efficient catalysts prevents the electrocatalytic reduction of carbon dioxide from contributing to the pressing target of a carbon-neutral economy. Indium-modified copper nitride was identified as a stable electrocatalyst selective toward CO. In2 O3 /Cu3 N showed a Faradaic efficiency of 80 % at 0.5 V overpotential for at least 50 h, in stark contrast to the very limited stability of the benchmark In2 O3 /Cu2 O. Microfabricated systems allowed to correlate activity with highly stable interfaces in indium-modified copper nitride. In contrast, fast diffusion of indium resulted in rapidly evolving interfaces in the case of the system based on oxide-derived Cu. A metastable nitrogen species observed by spectroscopic means was proposed as the underlying cause leading to the unchanging interfaces. This work reveals the stabilizing properties of nitride-derived copper toward high-performance multicomponent catalysts.

RESUMEN

Developing efficient and earth-abundant electrocatalysts for electrochemical water splitting is greatly desired due to growing energy demands. Herein, we develop a promising hierarchical nickel-iron-copper nitride electrode that is fabricated via a three-step process, starting with a hydrothermal synthesis of nickel-iron hydroxide on nickel foam and followed by the direct growth of copper metal-organic frameworks and, finally, low temperature ammonization. This approach yields a material that is an efficient catalyst for both the oxygen evolution reaction and the hydrogen evolution reaction. The as-fabricated heterostructured nickel-iron-copper nitride electrode exhibits an excellent activity with an overpotential of only 121 mV for the oxygen evolution reaction and an even a lower overpotential of 33 mV for the hydrogen evolution reaction. Additionally, this structure displays strong long-term stability with only a negligible increase in potential after 500 cycles of uninterrupted cyclic voltammetry testing. To the best of our knowledge, this as-prepared hierarchical nickel-iron-copper nitride is one of the most promising alternatives for the electrochemical oxygen and hydrogen evolution reactions.

RESUMEN

Copper nitride particles have a low decomposition temperature, they absorb light, and are oxidation-resistant, making them potentially useful for the development of novel wiring inks for printing circuit boards by means of intense pulsed light (IPL) sintering at low-energy. Here, we compared the thermal decomposition and light absorption of copper materials, including copper nitride (Cu3N), copper(I) oxide (Cu2O), or copper(II) oxide (CuO). Among the copper compounds examined, copper nitride had the second highest light absorbency and lowest decomposition temperature; therefore, we concluded that copper nitride was the most suitable material for producing a wiring ink that is sintered by means of IPL irradiation. Wiring inks containing copper nitride were compared with those of wiring inks containing copper nitride, copper(I) oxide, or copper(II) oxide, and copper conversion rate and sheet resistance were also determined. Under low-energy irradiation (8.3 J cm-2), copper nitride was converted to copper at the highest rate among the copper materials, and provided a sheet resistance of 0.506 Ω sq-1, indicating that copper nitride is indeed a candidate material for development as a wiring ink for low-energy intense pulsed light sintering-based printed circuit board production processes.

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AIM: To investigate osteoconductive and antimicrobial properties of a titanium-copper-nitride (TiCuN) film and an additional BONIT® coating on titanium substrates. METHODS: For micro-structuring, the surface of titanium test samples was modified by titanium plasma spray (TPS). On the TPS-coated samples, the TiCuN layer was deposited by physical vapor deposition. The BONIT® layer was coated electrochemically. The concentration of copper ions released from TiCuN films was measured by atomic absorption spectrometry. MG-63 osteoblasts on TiCuN and BONIT® were analyzed for cell adhesion, viability and spreading. In parallel, Staphylococcus epidermidis (S. epidermidis) were cultivated on the samples and planktonic and biofilm-bound bacteria were quantified by counting of the colony-forming units. RESULTS: Field emission scanning electron microscopy (FESEM) revealed rough surfaces for TPS and TiCuN and a special crystalline surface structure on TiCuN + BONIT®. TiCuN released high amounts of copper quickly within 24 h. These release dynamics were accompanied by complete growth inhibition of bacteria and after 2 d, no planktonic or adherent S. epidermidis were found on these samples. On the other hand viability of MG-63 cells was impaired during direct cultivation on the samples within 24 h. However, high cell colonization could be found after a 24 h pre-incubation step in cell culture medium simulating the in vivo dynamics closer. On pre-incubated TiCuN, the osteoblasts span the ridges and demonstrate a flattened, well-spread phenotype. The additional BONIT®coating reduced the copper release of the TiCuN layer significantly and showed a positive effect on the initial cell adhesion. CONCLUSION: The TiCuNcoating inhibits the formation of bacterial biofilms on orthopedic implants by influencing the "race for the surface" to the advantage of osteoblasts.

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It is highly attractive to develop non-noble-metal nanoarray architecture as a 3D-catalyst electrode for molecular detection due to its large specific surface area and easy accessibility to target molecules. Here, we report the development of a copper-nitride nanowires array on copper foam (Cu3 N NA/CF) as a dual-functional catalyst electrode for efficient glucose oxidation in alkaline solutions and hydrogen peroxide (H2 O2 ) reduction in neutral solutions. Electrochemical tests indicate that such Cu3 N NA/CF possesses superior non-enzymatic sensing ability toward rapid glucose and H2 O2 detection with high selectivity. At 0.40 V, this sensor offers a high sensitivity of 14 180 µA mm cm-2 for glucose detection, with a wide linear range from 1 µm to 2 mm, a low detection limit of 13 nm (S/N=3), and satisfactory stability and reproducibility. Its application in determining glucose in human blood serum is also demonstrated. Amperometric H2 O2 sensing can also been realized with a sensitivity of 7600 µA mm cm-2 , a linear range from 0.1 µm to 10 mm, and a detection limit of 8.9 nm (S/N=3). This 3D-nanoarray architecture holds great promise as an attractive sensing platform toward electrochemical small molecules detection.

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Within the first two years after total hip arthroplasty implant-associated infection has become the second most common reason for a revision surgery. Two-stage implant exchange is frequently conducted using temporary spacers made of antibiotic-loaded cement in order to prevent a bacterial colonization on the spacer. Avoiding several disadvantages of cement spacers, a conventional hemi-endoprosthesis was equipped with a copper-containing implant coating for inhibition of bacterial biofilms. In the present paper details of this novel treatment concept are presented including a case report.