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Spin‐polarized density functional theory (DFT) +U calculation was performed to study propylene selective oxidation on Cu2O(111) and Cl−Cu2O(111) surfaces. The mechanism included two pathways: the allylic hydrogen stripping (AHS) pathway and the epoxidation pathway, and acrolein, propylene oxide (PO), propanal and acetone can be formed. The calculated results found that the C3H6*+OO*→OOMMP2*→PO* route can be regarded as the preferred formation route of PO on these two surfaces. On clean surface, acrolein can be regarded as the main product, then other products selectivity follows: acetone>PO>propanal. On Cl−Cu2O(111) surface, acrolein was also the main product, and the apparent activation energy of acrolein (1.97 eV) was approximated to the apparent activation energy of PO (2.04 eV), other products selectivity follows: PO>propanal>acetone, which means that the selectivity of PO can be improved by the effect of Cl. Microkinetic simulation confirm that PO selectivity can be elevated qualitatively, and found that OOMMP2*→PO2*+O* is the rate determining step on pure surface and C3H6*+OO*→OOMMP2* is the rate controlling step on the doped−Cl surface. From this work, it can be found the O−O bond in O2 can be activated effectively by the presence of Cl, enhancing the selectivity of PO. [ABSTRACT FROM AUTHOR]

In this work, a composite material for the adsorption removal of thiophenic sulfur compounds (TSCs) was prepared by loading Cu2O onto palygorskite using a simple and low‐cost impregnation method and characterized for its structure and morphology. The addition of Cu2O did not change palygorskite's structure, and the Cu+ was evenly dispersed in the palygorskite fibers. The palygorskite provided the adsorptive active centers Cu+ efficient surface and pore structure to increase the sulfur removal performance of palygorskite. The optimum desulfurization process conditions of the Cu2O/palygorskite were obtained experimentally and by response surface methodology. With solid/liquid mass ratio of 1/100 and temperature of 30°C, the maximum static adsorption capacity of the Cu2O/palygorskite in model oil, which was composed of n‐octane and a single TSC at 400 mg S/L, showed an increase of 639% for thiophene, 543% for benzothiophene, and 563% for dibenzothiophene compared to palygorskite alone. In addition, the pseudo‐second‐order kinetic and Langmuir isotherm model exhibited the most fitting results for thiophene adsorbing on the composite, indicating that chemisorption on a monolayer basis plays a key role in the adsorption process. To sum up, these results suggest the composite has some potential in the field of adsorption‐desulfurization materials. [ABSTRACT FROM AUTHOR]

It is expected that the activity of photocatalysts can remain the same or decrease as little as possible in photocatalysis reaction. Herein, for the first time, a self‐accelerating H2 production activity in a noble‐metal‐free Cu2O/TpPa‐2‐COF photocatalyst is reported. It shows a beginning H2 production rate of 4.41 mmol h−1 g−1 under visible light illuminance, while the activity kept increasing to 27.27 mmol h−1 g−1 after 25 h reaction, which is 6.2 times higher than the beginning activity and reaches a record high. It is confirmed that part of Cu2O in Cu2O/TpPa‐2‐COF in situ transformed to Cu0 in photocatalytic reaction, which acting as cocatalyst promotes the separation of photogenerated charge carriers. Further density functional theory calculations demonstrate that the Schottky barrier height of Cu‐Cu2O (111) interface is much smaller than that of Pt‐Cu2O (111), supporting its more efficient effect than that with Pt as cocatalyst. [ABSTRACT FROM AUTHOR]

Cu2O has emerged as a promising material for sustainable hydrogen production through photoelectrochemical (PEC) water splitting, while inefficient charge separation remains one of the main challenges hindering its development. In this work, a new architecture of InAlN/Cu2O heterojunction photocathode is demonstrated by combining n‐type InAlN and p‐type Cu2O to improve the charge separation efficiency, thus enhancing PEC water‐splitting performance. The Pt/InAlN/Cu2O photoelectrode exhibits a photocurrent density of 2.54 mA cm−2 at 0 V versus reversible hydrogen electrode (VRHE), which is 3.21 times higher than that of Cu2O (0.79 mA cm−2 at VRHE). The enhanced PEC performance is explained by the larger built‐in potential Vbi of 1.43 V formed at the InAlN/Cu2O p–n junction than that in the single Cu2O photocathode (Vbi < 0.77 V), which improves the separation of the photogenerated carriers and thus relieves the bottlenecks of charge‐transfer kinetics at the electrode bulk and electrode/electrolyte interface. In this work, an avenue is opened for designing III‐nitrides/Cu2O heterojunction toward solar energy conversion. [ABSTRACT FROM AUTHOR]

Copper (Cu) is evidenced to be effective for constructing advanced catalysts. In particular, Cu2O is identified to be active for general catalytic reactions. However, conflicting results regarding the true structure‐activity correlations between Cu2O‐based active sites and efficiencies are usually reported. The structure of Cu2O undergoes dynamic evolution rather than remaining stable under working conditions, in which the actual reaction cannot proceed over the prefabricated Cu2O sites. Therefore, the dynamic construction of Cu2O active sites can be developed to promote catalytic efficiency and reveal the true structure‐activity correlations. Herein, by introducing the redox pairs of Cu2+ and reducing sugar into a photocatalysis system, it is clarified that the Cu2O sub‐nanoclusters (NCs), working as novel active sites, are on‐site constructed on the substrate via a photoinduced pseudo‐Fehling's route. The realistic interfacial charge separation and transformation capacities are remarkably promoted by the dynamic Cu2O NCs under the actual catalysis condition, which achieves a milestone efficiency for nitrate‐to‐ammonia photosynthesis, including the targets of production rate (1.98±0.04 mol gCu−1 h−1), conversion ratio (94.2±0.91 %), and selectivity (98.6 %±0.55 %). The current work develops an effective strategy for integrating the active site construction into realistic reactions, providing new opportunities for Cu‐based chemistry and catalysis sciences research. [ABSTRACT FROM AUTHOR]

Photocatalytic technology has great potential in water pollution treatment. Prepared Fe3+‐doped Cu2O photocatalyst using solvothermal method successfully in this paper. Analyze and test the prepared samples and study their photocatalytic performance. The prepared samples have high purity and their morphology has undergone changes. By introducing Fe3+, the specific surface area of the sample increases and the absorption of visible light significantly increases. Further research found that the degree of hole separation of photogenerated electrons is obviously improved, this is due to a significant reduction in the surface resistance of the sample. The R2‐Cu2O degradation rate reached 80.5 % and it shows excellent photocatalytic performance. [ABSTRACT FROM AUTHOR]

Enhancing the photocatalytic stability of Cu2O in the degradation of tetracycline is a great challenge in combating environmental water pollution because it is prone to deactivation by photocorrosion in aqueous environment. In this study, Cu2O/cellulose microfiber aerogel is synthesized through freeze‐drying, utilizing the self‐curling effect of cellulose and then calcined to produce Cu2O/C composite aerogel. The derived Cu2O/C composite aerogel features hollow carbon microfibers anchored with Cu2O nanocubes. Due to the curling structure and conductivity of the carbon microfibers, the photodegradation efficiency of the obtained Cu2O/C composite aerogel for tetracycline is drastically improved to 97.3% under 120 min of visible‐light irradiation, and remains a cycling photodegradation rate of 84.3% after 10 cycles. The Cu2O/C composite aerogel shows remarkable strategies for designing and constructing Cu2O‐based photocatalyst in the practical photodegradation of tetracycline under visible‐light exposure. [ABSTRACT FROM AUTHOR]

Cu2O has great advantages for CO2 electroreduction to C2 products, of which the activity and selectivity are closely related to its crystal facets. In this work, density functional theory calculation indicated that the (110) facets of Cu2O had a lower energy barrier for the C−C coupling compared to the (100) and (111) facets. Therefore, Cu2O(110) facets were successfully synthesized with the assistance of trace amounts of the ionic liquid 1‐butyl‐3‐methylimidazolium ([Bmim]BF4) by a sample wet‐chemical method. A high faradaic efficiency of 71.1 % and a large current density of 265.1 mA cm−2 toward C2H4 and C2H5OH were achieved at −1.1 V (vs. reversible hydrogen electrode) in a flow cell. The in situ and electrochemical analysis indicated that it possessed the synergy effects of strong adsorption of *CO2 and *CO, large active area, and excellent conductivity. This study provided a new way to enhance the C2 selectivity of CO2 electroreduction on Cu2O by crystal structure engineering. [ABSTRACT FROM AUTHOR]

Carbon dioxide electroreduction has been considered as one of the most appealing ways to reducing the CO2 emission but raising the selectivity of high‐value added products like C2+ still faces great challenge. Herein, we report a convenient way to modify the cubic Cu2O particles through UV‐light irradiation induced reduction in a solution containing H2O2 and i‐propanol. The plane surface of Cu2O was reconstructed to roughness shell composed of abandant grain boundaries, in which the ration of Cu+/Cu0 can be easily regulated by controlling the irradiation time. At the same time, the increasing electrochemical active surface area facilitated the exposure of active sites. Combining of above factors, the Faradaic efficiency of C2 (ethylene and ethanol) from CO2 electroreduction was greatly increased to 62.56% with a high partial current density of 145 mA cm−2. Our work put forward a facile method for the fine control of the surface structure of cuprous oxide and a novel platform to elucidate the synergistic effects of Cu+/Cu0 on CO2 electroreduction. [ABSTRACT FROM AUTHOR]

Photocatalytic degradation technology, using solar energy as the driving force, is considered the most possible alternative to remediate environmental pollution. And it is essential to find a stable and efficient photocatalyst. As promising semiconductor‐based photocatalysts, Cu2O has acquired massive attention owning to its high conduction band energy, superior visible‐light response‐ability, low cost, eco‐friendly, and abundance. However, the application of origin Cu2O faces severe problems due to its photocorrosion and low photoinduced carrier separation. Consequently, it is necessary to improve its photostability and photocatalytic activity by carrying out numerous modification strategies, such as heterostructure construction. Herein, we first summarize the classification and operation principles of Cu2O‐based type‐II heterojunction. Then, the application of the Cu2O‐based type‐II heterojunction photocatalysts for the removal of tetracyclines, quinolones, and sulfonamides have been discussed. Finally, the pressing issues and perspectives in Cu2O‐based type‐II heterojunction photocatalysts application for degrading antibiotics have prospected. [ABSTRACT FROM AUTHOR]

Copper oxide‐based materials effectively electrocatalyze carbon dioxide reduction (CO2RR). To comprehend their role and achieve high CO2RR activity, Cu+ in copper oxides must be stabilized. As an electrocatalyst, Cu2O nanoparticles were decorated with hexagonal boron nitride (h‐BN) nanosheets to stabilize Cu+. The C2H4/CO ratio increased 1.62‐fold in the CO2RR with Cu2O−BN compared to that with Cu2O. Experimental and theoretical studies confirmed strong electronic interactions between the two components in Cu2O−BN, which strengthens the Cu−O bonds. Electrophilic h‐BN receives partial electron density from Cu2O, protecting the Cu−O bonds from electron attack during the CO2RR and stabilizing the Cu+ species during long‐term electrolysis. The well‐retained Cu+ species enhanced the C2 product selectivity and improved the stability of Cu2O−BN. This work offers new insight into the metal‐valence‐state‐dependent selectivity of catalysts, enabling the design of advanced catalysts. [ABSTRACT FROM AUTHOR]

Herein, the widely available and cheapest cuprous oxide (Cu2O) as hole transport layer (HTL) is proposed to improve the performance of thin‐film copper indium gallium selenide (CIGS) solar cell. Solar Cell Capacitance Simulator in One Dimension (SCAPS‐1D) is utilized to design and study output characteristics of the modeled photovoltaic (PV) cell. A comparison between the proposed cell with Cu2O HTL and the reference CIGS solar cell is presented. The PV performances of CIGS solar cells are analyzed by changing thickness, carrier density and defects of different layers, operating temperatures, and recombination velocity at back contact. Optimal thicknesses of Cu2O HTL, CIGS absorber, cadmium sulfide (CdS) buffer, and the fluorine‐doped tin oxide (FTO) window layer are obtained to be 0.3, 0.8, 0.05, and 0.05 μm, respectively. Efficiency of 30.30% is achieved for the proposed CIGS PV device with Cu2O HTL. The simulated results imply that the proposed Cu2O as HTL can be used to show proficient and cost‐effective thin‐film CIGS PV cells. [ABSTRACT FROM AUTHOR]

Based on the great advantages of an inner hollow structure and excellent solid counterpart capacity, complex hierarchical structures have been widely used as electrodes for lithium‐ion batteries. Herein, hierarchical yolk–shell Cu2O@CuO‐decorated RGO (YSRs) was designed and synthesized via a multi‐step approach. Octahedron‐like Cu2O‐decorated RGO was firstly produced, in which GO was reduced slightly while cuprous oxide was synthesized. Subsequently, the controlled oxidation of Cu2O@RGO led to the synthesis of special YSRs, which were composed of a solid Cu2O core, spur‐CuO, CuO shell, and RGO covered. As anode materials, YSRs could provide considerable capacity density. Meanwhile, the void existed between shells and solid active materials retaining the advantages of inner hollow structure. As a result, the unique architecture of the materials renders the composites with enhanced electronic and ionic diffusion kinetics, high specific capacity (~894 mAh g‐1, 0.1C), and an excellent rate capability. [ABSTRACT FROM AUTHOR]

Photoelectrochemical (PEC) cells using Cu2O, semiconductor photoabsorbers passivated by protection layers, show a trade‐off between high photocurrent and stability because of the thickness of the energy band transport along the conduction band. Based on nanofilaments with non‐volatile metal‐like current flow characteristics in resistance‐change memory devices, a strategically advanced conducting filament transport mechanism for vigorous and robust PEC operation is proposed. The breakdown‐like electrochemical forming behavior effectively occurs with a rapid increase in current at ≈2 V (vs RHE). The fundamental properties of filaments, such as diameter, density, and conductivity, are controlled by varying the artificial compliance currents. This process does not require any top electrodes that obstruct light‐harvesting and the injection of photo‐charges into electrolytes or individual forming process with point‐by‐point sweeping, and provides electrochemical forming sites with homogeneous and dense distribution. Additionally, some photocorrosive sites that induce photocurrent degradation are passivated by the preferential photoelectrodeposition of co‐catalysts. From the electrochemical filament forming process and selective Pt‐photoelectrodeposition on filaments, the Cu2O/AZO/TiO2 photocathodes exhibit an unprecedented photocurrent density of ≈11.9 mA cm−2 and open‐circuit potential of 0.73 V and produce vigorous hydrogen and oxygen evolutions for over 100 h, even when the TiO2 passivation film exceeds 100 nm in thickness. [ABSTRACT FROM AUTHOR]

Oxide semiconductor‐TFT technology is widely accepted as a technology that realizes next‐generation display and flexible device technologies. However, the absence of high‐performance p‐channel oxide‐TFT is still recognized as the largest technological barrier that hinders the potentials of the oxide‐TFT device application. Here we investigated the TFT characteristics of p‐channel SnO and Cu2O oxide‐TFTs and clarified the origin of the poor TFT characteristics. It was found that their TFT performances for both the devices are largely affected backchannel donor‐type defect. We also developed effective backchannel defect termination for p‐channel oxide‐TFTs to improve their p‐channel TFT characteristics. [ABSTRACT FROM AUTHOR]

Direct conversion of carbon dioxide into multicarbon liquid fuels by the CO2 electrochemical reduction reaction (CO2RR) can contribute to the decarbonization of the global economy. Here, well‐defined Cu2O nanocubes (NCs, 35 nm) uniformly covered with Ag nanoparticles (5 nm) were synthesized. When compared to bare Cu2O NCs, the catalyst with 5 at % Ag on Cu2O NCs displayed a two‐fold increase in the Faradaic efficiency for C2+ liquid products (30 % at −1.0 VRHE), including ethanol, 1‐propanol, and acetaldehyde, while formate and hydrogen were suppressed. Operando X‐ray absorption spectroscopy revealed the partial reduction of Cu2O during CO2RR, accompanied by a reaction‐driven redispersion of Ag on the CuOx NCs. Data from operando surface‐enhanced Raman spectroscopy further uncovered significant variations in the CO binding to Cu, which were assigned to Ag−Cu sites formed during CO2RR that appear crucial for the C−C coupling and the enhanced yield of liquid products. [ABSTRACT FROM AUTHOR]

Die direkte Umwandlung von Kohlendioxid zu flüssigen Brennstoffen durch die elektrochemische Reduktion von CO2 (CO2RR) kann zu der Dekarbonisierung der weltweiten Wirtschaft beitragen. Hier wurden wohldefinierte Cu2O‐Nanowürfel (NW, 35 nm) synthetisiert, die einheitlich mit Ag‐Nanopartikeln (5 nm) bedeckt wurden. Verglichen mit den reinen Cu2O‐NW zeigte der Katalysator mit 5 at % Ag auf den Cu2O‐NW einen zweifachen Anstieg in der Faraday‐Effizienz für C2+‐Flüssigprodukte (30 % bei −1.0 VRHE) einschließlich Ethanol, 1‐Propanol und Acetaldehyd. Dagegen wurden Formiat und Wasserstoff unterdrückt. Operando‐Röntgenabsorptionsspektroskopie enthüllte die teilweise Reduktion von Cu2O während CO2RR, begleitet von einer reaktionsgetriebenen Redispersion von Ag auf den CuOx‐NW. Operando‐oberflächenverstärkte Raman‐Spektroskopie deckte außerdem signifikante Veränderungen in der CO‐Bindung zu Cu auf, die wir auf die während der CO2RR neugebildeten Ag‐Cu‐Zentren zurückführen. Folglich spielt Ag‐Cu eine zentrale Rolle für die C‐C‐Kupplung und der damit verbundenen erhöhten Ausbeute an Flüssigprodukten. [ABSTRACT FROM AUTHOR]

Cs2AuBiCl6 is considered to be a potential lead‐free double perovskite alternative for perovskite solar cells. Its electronic and optical properties are investigated using density functional theory. The electronic properties of Cs2AuBiCl6 material ensure a bandgap of 1.40 eV (without considering SOC) and 1.12 eV (with SOC) using mBJ exchange‐correlation functional, close to the optimal bandgap for solar cell application as per the Shockley–Queisser limit. Optical properties suggest a high absorption coefficient ≈105 cm−1 with low reflectance, making it the optimal absorber material. Furthermore, the photovoltaic performance of Cs2AuBiCl6 based single‐junction transparent conducting oxide (TCO)/IDL1/Cs2AuBiCl6/IDL2/Cu2O solar cell is investigated using SCAPS‐1D device simulation program. The impact of electron affinity, thickness, carrier concentration, defect density, and interface defect density is examined using interface defect layer (IDL) on the photovoltaic performance. The maximum photoconversion efficiency (PCE) of ≈22.18% is noticed for optimized material's parameters. These studies on TCO/IDL1/Cs2AuBiCl6/IDL2/Cu2O solar cell will provide guidelines for designing and developing an efficient lead‐free perovskite‐based solar cell as an alternative to conventional halide perovskite materials based solar cell. [ABSTRACT FROM AUTHOR]

Cu2O, a photoactive p‐type semiconductor based on earth‐abundant elements, shows promising features for photoelectrochemical CO2 reduction reaction (PEC CO2RR). However, despite the broad light absorption and appropriate conduction band edge energy, it promptly undergoes photocorrosion in PEC CO2RR conditions. Herein, we evaluate an amine‐functionalized polysiloxane (AF−PSi) as both protective layer and PEC CO2RR promoter via amine‐CO2 adduct formation. Electrochemistry experiments and X‐ray diffraction showed that photostability is significantly enhanced with AF−PSi overlayer. Electrolyses experiments under visible light irradiation indicated selective production of formate with faradaic efficiency of 61 % at low overpotential. Detailed in situ FTIR studies revealed that amine groups bind to CO2 to form carbamate species and that this process is favoured by cathodic polarization, confirming the dual role of AF−PSi layer. [ABSTRACT FROM AUTHOR]

Bulk metal oxide catalysts are key components of numerous large‐scale industrial processes that possess a high degree of complexity in bulk and surface structure. Such complexity manifests itself in the form of large uncertainties with respect to the nature, density, and efficacy of active sites responsible for catalytic turnovers. Faceted oxide crystals present the prospect of exposing well‐defined oxide surfaces while also being amenable for investigation at realistic pressures and temperatures. Despite the opportunity faceted oxide crystals present for developing more rigorous relationships between atomic‐level structure and catalytic function, their use remains far less prevalent compared to their metallic counterparts. This review, focused on cuprous oxide and cerium oxide crystals, seeks to examine and highlight challenges in controlling and rationalizing metal oxide crystallization, as well as limitations preventing elucidation of the relationships between atomic‐level structures and catalytic properties. We postulate that a clearer understanding of these challenges will encourage researchers to further pursue the study of catalytic properties of faceted oxide crystals, aiding not only an enhanced molecular‐level knowledge of bulk oxide catalysis, but also the development of improved materials for large‐scale catalytic processes. [ABSTRACT FROM AUTHOR]

Hierarchical Cu2O nanospheres with a Pompon Dahlia‐like morphology were prepared by a one‐pot synthesis employing electrostatic self‐assembly. Nanocomposite analogues were also prepared in the presence of reduced graphene oxide (rGO). Photophysical properties of the hierarchical Cu2O nanospheres and Cu2O/rGO nanocomposite were determined, and their photocatalytic applications evaluated for photocatalytic 4‐chlorophenol (4‐CP) degradation and H2 production. Introduction of trace (<1 wt %) rGO improves the apparent quantum efficiency (AQE) at 475 nm of hierarchical Cu2O for H2 production from 2.23 % to 3.35 %, giving an increase of evolution rate from 234 μmol.g−1.h−1 to 352 μmol.g−1.h−1 respectively. The AQE for 4‐CP degradation also increases from 52 % to 59 %, with the removal efficiency reaching 95 % of 10 ppm 4‐CP within 1 h. Superior performance of the hierarchical Cu2O/rGO nanocomposite is attributable to increased visible light absorption, reflected in a greater photocurrent density. Excellent catalyst photostability for >6 h continuous reaction is observed. [ABSTRACT FROM AUTHOR]

Real‐time visualization of the positions of micro/nanomotors is highly desired for practical applications due to the complex environments that they are used in. However, most reported photocatalytic micromotors can only be tracked in transparent solutions under bright fields, which greatly limits their applications. Herein, photocatalytic micromotors based on Cu2O@carbon dot (CDot) particles with excellent fluorescent properties and precise propulsion capabilities in 3D are reported. In the fully green environment of malic acid, the Cu2O@CDot micromotors display efficient propulsion under visible light irradiation (as high as 40.85 μm s−1). In addition, the propulsion direction of the Cu2O@CDot micromotors can be effectively adjusted by changing the direction of light via positive phototaxis. Interestingly, due to the presence of CDots, these new Cu2O@CDot micromotors display excellent and stable fluorescence. This study reports the first photocatalytic micromotors with both novel fluorescence properties and excellent propulsion characteristics in biocompatible environments. Due to their excellent fluorescent properties and precise motion control, these Cu2O@CDot micromotors hold great potential to perform complex tasks across diverse practical applications. [ABSTRACT FROM AUTHOR]

The design of efficient catalyst is of great importance in pyrazole derivatives synthesis. Herein, rhombic dodecahedra Cu2O microcrystals were successfully synthesized, and employed as catalysts in the direct synthesis of alkenyl pyrazoles. The catalytic activity of the obtained Cu2O catalyst toward the synthesis of alkenyl pyrazoles via the reaction of p‐chlorophenyl hydrazone and 2,4‐pentanedione was studied. The results showed that the high yields of alkenyl pyrazoles was achieved by using a rhombic dodecahedra Cu2O catalyst. Moreover, the rhombic dodecahedra also exhibited excellent catalytic activity for a variety of different hydrazones, which demonstrates their potential as a versatile catalyst. The Cu2O catalyst shows good reusability. Hence, the rhombic dodecahedra Cu2O microcrystals can be viewed as a highly useful catalyst for synthesis of alkenyl pyrazoles. [ABSTRACT FROM AUTHOR]

The synthesis of phase‐pure, narrow‐size‐distributed and highly stable Cu2O nanocrystals is reported, which can be processed as hole‐transporting layers (HTLs) in solution‐processed optoelectronic devices. The synthesis is based on a thermal decomposition process with a ligand protection strategy. The reactivity of precursor can be tuned by simply modulating the concentration of oleylamine in non‐coordinated solvent, resulting in effectively controlling the size and size distribution of Cu2O nanocrystals. Combined with ligand protection strategy of using lithium stearate and moderate reaction temperature of 170 °C, in situ aggregation of Cu2O nanocrystals could be inhibited, exhibiting excellent stability in hexane for several months. The resulting phase‐pure colloidal Cu2O particles (after ozone‐treatment) were applied as HTLs in polymer light‐emitting diodes, the performance of which are comparable to that of the poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) based devices. [ABSTRACT FROM AUTHOR]

We demonstrate that Cu2O particles can be produced along with siloxene formation by simply dispersing layered CaSi2 into an aqueous solution of CuCl2 and HCl at room temperature. The Cl− ions induce oxidative extraction of Ca from CaSi2 to form siloxene and trigger the reductive deposition of Cu particles. All particles are then gradually oxidized to form Cu2O particles under optimized conditions as follows. A trace amount of residual CaSi2 is dissolved in the solution, which provides OH− ions, and a portion of the formed Cu particles are dissolved as [Cu(OH)4]2− ions. Accordingly, Cu2O particles would be formed through the comproportionation reaction between Cu and [Cu(OH)4]2− ions in the solution. However, under conditions with an excess amount of Cl− ions results in further oxidation of Cu to also form Cu2Cl(OH)3. Thus, CaSi2 acts as an effective reduction and/or oxidation mediator to tune the number of Cl− and OH− ions and control the oxidation state of Cu. [ABSTRACT FROM AUTHOR]

In this work, we study the effect of Cu2O film obtained from a fully reacted Cu seed layer as a photoelectrode in photoelectrochemical cells. The full reaction of the Cu layer shows an enhanced photocurrent density and improved efficiency in hydrogen evolution. The photocurrent density of textured Cu2O (0.58 mA cm−2 at 0 V vs. RHE), without an unreacted Cu layer is two times higher than films containing an unreacted Cu layer (0.29 mA cm−2 at 0 V vs. RHE), under AM 1.5 illumination (100 mW cm−2). The thickness of the unreacted Cu layer influences significantly the charge transfer process at the interface between the Cu2O and electrolyte. The enhanced photoelectrochemical performance of textured Cu2O is attributed to the reduced charge recombination resulting from a longer carrier lifetime in the Cu2O layer. Experimentally we confirmed that the unreacted Cu layer inhibits the photoelectrochemical performance of Cu2O‐based photocathodes. The elimination of the unreacted Cu layer leads to higher photocurrent density. [ABSTRACT FROM AUTHOR]

To prevent photocorrosion of a Cu2O photocathode, composition of a TiO2 layer onto the Cu2O is one of the most effective solutions. For crystallization of the TiO2 layer alone without heat‐damage to the underlying Cu2O layer, which is easy to oxidize to CuO, we developed the integration process of O2‐plasma and an excimer‐laser irradiation, that a metal‐organic precursor film is crystalized by irradiation of the excimer‐laser in O2‐plasma. The TiO2 layer could be crystalized with lower oxygen vacancies by the laser irradiation in O2‐plasma compared to that prepared by the irradiation in air. Furthermore, the oxidation of Cu2O to CuO was drastically restricted due to the highly crystalized TiO2 in which oxygen ions were hard to diffuse to the interface of TiO2/Cu2O. The photocorrosion of the obtained film during water reduction reaction was also restricted. This O2‐plasma integrated process is effective for selective crystallization of metal‐oxide films for functionalization of photoelectrodes. [ABSTRACT FROM AUTHOR]

Unique octahedral yolk‐shell Cu2O@Co(OH)2 nanocages are synthesized by a facile Cu2O self‐templated strategy as efficient glucose oxidation electrocatalysts. Amorphous Co(OH)2 nanoflakes are formed as octahedral shells through coordinating etching conversion from part of Cu2O templates. The un‐etched crystalline Cu2O octahedrons are then remained as cores and voids exist between the cores and shells. The special structure endow these yolk‐shell heterostructure nanocages with abundant active sites, large surface area, and synergistic effect between Cu2O and Co(OH)2. The octahedral yolk‐shell Cu2O@Co(OH)2 nanocages demonstrate superior electrocatalytic activity for glucose oxidation in terms of high sensitivity of 1340 μA cm−2 mM−1, low detection limit of 2 μM, wide linear sensing range, and long‐term stability. This strategy might shed lights on the synthesis of various yolk‐shell heterostructure nanocages with controllable structures and enhanced catalytic performances. [ABSTRACT FROM AUTHOR]

Abstract: Well‐defined Cu2O nanocubes with tunable dimensions and physicochemical properties have been prepared using a simple one‐pot reaction. Reduction of Cu(II) salts by ascorbic acid in the presence of PEG as a structure‐directing agent affords crystalline Cu2O nanocubes of between 50 to 500 nm. Optical band gap, band energies, charge‐carrier lifetimes and surface oxidation state systematically evolve with nanocube size, and correlate well with visible light photocatalytic activity for aqueous phase phenol degradation and H2 production which are both directly proportional to size (doubling between 50 and 500 nm). HPLC reveals fumaric acid as the primary organic product of phenol degradation, and selectivity increases with nanocube size at the expense of toxic catechol. Apparent quantum efficiencies reach 26 % for phenol photodegradation and 1.2 % for H2 production using 500 nm Cu2O cubes. [ABSTRACT FROM AUTHOR]

For developing semiconductor junction devices with low cost electrodeposited cuprous oxide (Cu2O), it will be very useful to investigate possibilities to improve the interface properties of Cu2O with suitable junction materials. We have investigated the effect of electrodeposition bath pH on the interfacial properties of n‐Cu2O/electrolyte, n‐Cu2O/Au, and n‐Cu2O/p‐Cu2O junctions by exploiting capacitance–voltage and photoresponse measurements. In addition, XRD and SEM measurements were also employed for thin film characterization. We have observed that for an increase in bath pH from 5.7 to 6.5 the resulted n‐Cu2O films produced a shift in the extrapolated flat band potential at the aqueous electrolyte interface by 300 mV. In addition, we have observed that extrapolated built‐in potentials at n‐Cu2O/Au and n‐Cu2O/p‐Cu2O interfaces are also affected by the bath pH. With the change in bath pH, the shift in the flat band potential at n‐Cu2O/electrolyte interface is completely opposite to the built‐in potential shift at n‐Cu2O/Au interface. We explained the observation as a result of the change in net charge at the interfacial surface layers of the interfaces, due to the change in bath pH of the films. Evidence in support of the explanation was further established by the observation that the built‐in potential at n‐Cu2O/Au interface is increased due to the surface modification of n‐Cu2O films with S2− ions. In addition, bath pH could be optimized in the fabrication process of Cu2O homojunctions to yield high photoactivity. In comparison with the best n‐Cu2O/Au Schottky junction, we could fabricate a Cu2O homojunction with a 590% increase in Voc and an 800% increase in Isc. All the experimental evidences directed toward the idea that the relative band edge position of n‐Cu2O at the interfaces is affected by the bath pH. The results reported in this investigation will be very useful in the applications of electrodeposited Cu2O films in photocataytic, solar cell, and other electronic devices. [ABSTRACT FROM AUTHOR]

Constructing tandem junction devices consisting of a bottom cell based on prevailing solar cell techniques such as silicon (Si) or Cu(In,Ga)(Se,S)2 (CIGS) combined with a perovskite top cell is one effective approach to improve photovoltaic device performance. An intermediate transparent conducting layer as one component of the tunnel junction connecting the two single devices, at the same time serving as inorganic hole transport material for the perovskite solar cell is one of the key components to realize a perovskite-CIGSe tandem structure. In this contribution, we describe the deposition of p-type Cu2O films at room temperature by magnetron sputtering using nitrogen doping to form a homogenous layer with high transparency and good conductivity, and the modeling of a monolithic perovskite-CIGSe tandem solar cell utilizing this layer. We applied the in-house software RefDex to illustrate the impact of Cu2O on the performance of a tandem device, and calculated the reflection, transmission, and absorption. [ABSTRACT FROM AUTHOR]

CuO and Cu2O are non-noble transition metal oxide supercapacitive materials with high theoretical specific capacitances above 1800 F g−1. In this work, by adjusting organic additives of a colloidal system, Cu, Cu2O, and CuO are grown in situ on nickel foam. CuO exhibits a specific capacitance of 1355 F g−1 at 2 A g−1 in 3 m KOH, a value well above those of Cu and Cu2O (<500 F g−1), and is superior to other known CuO electrodes. The CuO electrode exhibits 70% of its initial capacity, and the Columbic efficiency remains ≈100% after 7000 cycles at 4 A g−1. Cu2O exhibits the worst electrochemical performance, mainly due to the inactive barrier layer forming on the surface. This work provides an efficient synthetic platform for both comparable supercapacitive studies and cost-effective electrochemical energy storage applications. [ABSTRACT FROM AUTHOR]

Thin films of nitrogen-doped cuprous oxide (Cu2O:N) have been deposited by means of direct-current and radio-frequency sputtering using a metallic copper target and a mixture of argon, oxygen, and nitrogen for generating the plasma. The doping with nitrogen appears to significantly increase the electrical conductivity of the films. All samples exhibit a temperature-activated transport behavior. It is shown that the activation energy decreases proportionally to the reciprocal distance between nitrogen atoms, which indicates that a constant fraction of nitrogen is most likely substitutionally incorporated on oxygen site in the Cu2O lattice and acts as an acceptor. Nevertheless, Raman measurements suggest that molecular nitrogen can also be found in the samples, bound at different sites inside the bulk and at the surface. [ABSTRACT FROM AUTHOR]

Si/Cu2O Schottky-junction photovoltaic devices are fabricated by the thermal deposition of a Cu2O thin film on a silicon surface that has been passivated with methyl (CH3) groups. X-ray photoelectron spectroscopy shows that the methyl-group passivation is efficient for suppressing the oxidation of silicon and the formation of CuxO species. The thermally deposited Cu2O presents a pure phase with a valance band edge at ( EF - 0.97) eV, where EF is the Fermi level. By optimizing the nanostructure of the silicon surface, air-stable devices with a maximum power conversion efficiency of 6.02% are achieved. Analysis of the dark current density as a function of voltage ( J-V curves) shows that the carrier transport through the Si-CH3/Cu2O junction deviates from the thermionic emission diode model because part of the applied voltage drops at the depletion layer as a result of the CH3 passivation. This explains the higher short-circuit current density ( JSC) and open-circuit voltage ( VOC) and the lower fill factor (FF) of the Si-CH3/Cu2O device relative to a device with H passivation. These findings provide insight into strategies for further improving the photovoltaic performance of the Si/Cu2O heterojunction. [ABSTRACT FROM AUTHOR]

A surfactant free template assisted electrodeposition method was used to fabricate thick n-type Cu2O films having cubic nanostructures for the detection of liquefied petroleum (LP) gas at low concentrations. Templates were fabricated by initially electrodepositing a p-type Cu2O thin film on a Ti substrate followed by annealing that changed conductivity type of the film, as confirmed by Mott-Schottky and spectral response measurements. SEM measurements of resulting films showed nano-cubic crystals having sizes of 150-300 nm. When exposed to a mixture of LP gas and dry air, the resistance of these films increased and the maximum response was recorded when films were maintained at 180 °C for all concentrations and it was independent of the surface morphology. At 180 °C, at the lowest tested LP gas concentration of 2 vol.%, a twofold increase in response was observed in the nano-cubic films compared to the micro-crystalline n-type Cu2O films. This improvement in gas response is attributed to increased effective surface area of these nanostructured films. Compared to other LP gas sensing materials, Cu2O films showed very good response times and recovery times of ∼120 and ∼90 s, respectively. [ABSTRACT FROM AUTHOR]

The effect of Cu/O/Ti interstitials on the visible-light absorption in Cu2O/TiO2 heterojunctions has been investigated by ab initio methods. The three interstitials are, respectively, doped at the interface of the Cu2O/TiO2 heterojunctions. The Ti interstitial efficiently improves the visible-light absorption, whereas the O interstitial reduces the visible-light absorption. An independent characteristic of the visible-light absorption is found for doping with the Cu interstitial. These phenomena originate from the different concentrations of delocalized electrons induced by the doping atom. The doping with Ti atoms could induce the aggregation of Cu ions, which release more delocalized electrons and so improve the visible-light absorption in a Cu2O/TiO2 heterojunction. [ABSTRACT FROM AUTHOR]

A simple, efficient Cu2O catalyst system under microwave irradiation was developed for N-arylation of various indoles without ligands and additives. Diverse N-heteroarylated indoles were prepared by coupling indoles with various heteroaryl halides within 1 h. The selective reactivity of bromoindole with aryl iodide provided N-aryl bromoindoles, which could be useful intermediates for palladium-catalyzed Heck and Suzuki coupling reactions. [ABSTRACT FROM AUTHOR]

The lack of a successful p-type transparent semiconductor delays the future implementation of transparent electronics. In the group semiconducting compounds, cuprous oxide (Cu2O) presents promising electrical and manufacturing features that establish it as a suitable candidate for p-type transparent semiconductors. However, high absorbance in the visible range reduces its application practical devices. In this work, we achieved the incorporation of magnesium in cuprous oxide grown by aerosol-assisted metal-organic chemical vapour deposition. The fabricated doped thin films reached up to 17% of magnesium, resulting in morphology changes. Electrical resistivity was reduced down to values as low as 6.6 Ωcm, due to the increase of charge-carrier density. The optical transparency was enhanced compared to intrinsic cuprous oxide. [ABSTRACT FROM AUTHOR]

In this paper a promising solution for the notorious problem of manufacturing a stable low ohmic back contact of a CdTe thin film superstrate solar cell is presented without using elemental copper. Instead we have used a Cu2O layer inserted between the CdTe absorber and metal contact (Au). In contrast to the barrier free band alignment gained by using the transitivity rules, XPS measurements show a barrier in the valence band of the Cu2O layers directly after deposition, which results in a low performing JV curve. The contact can be improved by a short thermal treatment resulting in efficiencies superior to copper based contacts for standard CdS/CdTe hetero junction solar cells prepared on commercial glass/FTO substrates. By replacing the CdS window layer with a CdS:O buffer layer efficiencies of >15% could be achieved. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The n-type and p-type cuprous oxide thin films were electrodeposited potentiostatically in acetate and lactate baths, respectively. Sulfur treatment of n-type and p-type cuprous oxide surfaces were achieved using gaseous (NH4)2S. Sulfur-treated Cu2O films were annealed in air at 100, 150, 200, 250, 350, and 450 °C for unique times to obtain the best photocurrent. Unannealed and annealed samples of sulfur-treated and untreated cuprous oxide were then investigated using high-energy X-ray diffraction (HEXRD). The HEXRD measurements and the pair distribution function (PDF) analysis revealed that the sulfur treatment leads to the formation of crystalline CuS on Cu2O film surfaces. The present study also shows that the sulfur treatment causes minor structural changes in Cu2O samples due to the formation of CuS. It was observed that the sulfur-treated cuprous oxide samples retarded the formation of CuO at higher temperatures showing good thermal stability and enhancement of the photoactivity of the n-type and p-type cuprous oxides. [ABSTRACT FROM AUTHOR]

Shape‐dependent catalysis and sensing behaviours are primarily focused on nanocrystals enclosed by low‐index facets, especially the three basic facets ({100}, {111}, and {110}). Several novel strategies have recently exploded by tailoring the original nanocrystals to greatly improve the catalysis and sensing performances. In this Review, we firstly introduce the synthesis of a variety of Cu2O nanocrystals, including the three basic Cu2O nanocrystals (cubes, octahedra and rhombic dodecahedra, enclosed by the {100}, {111}, and {110} facets, respectively), and Cu2O nanocrystals enclosed by high‐index planes. We then discuss in detail the three main facet‐controlled synthetic strategies (deposition, etching and templating) to fabricate Cu2O‐based nanocrystals with heterogeneous, etched, or hollow structures, including a number of important concepts involved in those facet‐controlled routes, such as the selective adsorption of capping agents for protecting special facets, and the impacts of surface energy and active sites on reaction activity trends. Finally, we highlight the facet‐dependent properties of the Cu2O and Cu2O‐based nanocrystals for applications in photocatalysis, gas catalysis, organocatalysis and sensing, as well as the relationship between their structures and properties. We also summarize and comment upon future facet‐related directions. [ABSTRACT FROM AUTHOR]

Strontium-doped Cu2O thin films were successfully grown through metalorganic chemical vapor deposition method. The films were characterized regarding their morphology, composition, electrical, and optical properties. The composition of the films, and especially their strontium concentration, is the dominant factor which mainly affects the morphology as well as the electrical film properties. Indeed, it was observed that an increase of the film strontium content decreases its resistivity, from 105 Ω cm for undoped Cu2O films to about 101 Ω cm for films doped with 5-6% strontium without any impact on their optical properties. However, for larger strontium contents, the Cu2O films also contain SrCO3 as impurity phase. [ABSTRACT FROM AUTHOR]

Morphology-controlled synthesis of cuprous oxide ( Cu2O) microcrystal was achieved using a solvothermal method. The morphologies of the Cu2O microcrystals, namely octahedral, truncated octahedral, truncated rhombic dodecahedral, and rhombic dodecahedral, were fine-tuned by varying the oleylamine and sodium oleate concentrations. Only the {111} and {110} facets of the Cu2O microcrystals were involved in this morphological transition. Octahedral Cu2O microcrystals were obtained in the absence of oleylamine and at the highest sodium oleate concentration. Rhombic dodecahedral Cu2O microcrystals were obtained at the highest oleylamine concentration or at the lowest sodium oleate concentration. The rhombic dodecahedron, which exposed only the {110} facets, exhibited better antibacterial activities against Escherichia coli compared to the octahedron, which exposed only the {111} facets. [ABSTRACT FROM AUTHOR]

We have developed a simple method for tuning the morphologies of Cu2O microcrystals. Cu2O microcrystals were prepared by precipitation at room temperature from a mixture of Cu(CH3COO)2·H2O, N,N,N',N'- tetramethyl ethylenediamine (TMEDA), ascorbic acid, and polyethylene glycol (PEG). TMEDA was used to promote the formation of copper-TMEDA complexes. A variety of Cu2O microcrystal morphologies were obtained simply by varying the concentrations of TMEDA and ascorbic acid. Aggregated Cu2O microspheres are formed at higher concentrations of ascorbic acid in the absence of TMEDA. Aggregated Cu2O microcubes are formed at lower concentrations of ascorbic acid and higher concentrations of TMEDA. The crystal growth mechanism of these Cu2O morphologies is explained. [ABSTRACT FROM AUTHOR]

Surface-enhanced Raman scattering of p-aminothiophenol and p-nitrothiophenol were obtained on the surface of Cu2O nanoparticles, showing novel spectral changes with morphology-dependent and time-dependent characteristics. The measured Raman signals were believed to partly originate from the newly produced surface species p,p′-dimercaptoazobenzene. The nature of surface chemisorption status during Raman measurement was investigated experimentally and theoretically via combined surface-enhanced Raman scattering and density functional theory study, indicating that surface catalytic reaction of p-aminothiophenol and p-nitrothiophenol could take place on the surface of oxide nanostructures as well as coinage metal material. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In low temperature grown ZnO/Cu2O solar cells, there is a discrepancy between collection length and depletion width in the Cu2O which makes the simultaneous achievement of efficient charge collection and high open-circuit voltage problematic. This is addressed in this study by fabricating ZnO/Cu2O/Cu2O+ back surface field devices using an atmospheric atomic layer deposition (AALD) printing method to grow a sub-200-nm Cu2O+ film on top of electrodeposited ZnO and Cu2O layers. The AALD Cu2O+ has a carrier concentration around 2 orders of magnitude higher than the electrodeposited Cu2O, allowing the electrodeposited Cu2O layer thickness in a back surface field cell to be reduced from 3 μm to the approximate charge collection length, 1 μm, while still allowing a high potential to be built into the cell. The dense conformal nature of the AALD layer also blocks shunt pathways allowing the voltage enhancement to be maintained. The thinner cell design reduces recombination losses and increases charge collection from both incident light and light reflected off the back electrode. Using this design, a short circuit current density of 6.32 mA cm−2 is achieved-the highest reported JSC for an atmospherically deposited ZnO/Cu2O device to date. [ABSTRACT FROM AUTHOR]

Crystallization of hopper-like Cu2O cubes is demonstrated in alkaline citrate-copper solution upon the equilibrium between complexation, precipitation and redox reactions. The complexation reactions of Na3cit and NaOH with Cu2+ manipulate the current chemical reaction routes, phase transformation, and thus crystallization morphologies and compositions. During the crystallization of Cu2O variations of mother solution such as pH and the concentration of Cu2+ (Cu+) are monitored by ex situ pH measurement and UV-Vis absorption spectroscopy. The shape evolution of Cu2O hopper cubes is consistent with the chemical reaction routes, which demonstrates the interplay between chemical reactions and crystal growth. The appropriate reaction concentration, Na3cit:Cu2+ > 2 and 1 < NaOH:Cu2+ < 2, has been identified for the growth of these hopper cubes. The current reaction-controllable crystal growth may further the synthesis chemistry toward rational control over crystallization. [ABSTRACT FROM AUTHOR]

We investigate the characteristics of Cu2OO thin films deposited through the addition of N2O gas. The addition of N2O gas has remarkable effects on the phase changes, resulting in improved electrical and optical properties. An intermediate phase (6CuO·Cu2O) appears at a N2O flow rate of 1 sccm, and a Cu2OO (200) phase is then preferentially grown at a higher feeding amount of N2O. The optical and electrical properties of Cu2O thin films are improved with a sufficient N2O flow rate of more than 15 sccm, as confirmed through various analyses. Under this condition, a high bandgap energy of 2.58 eV and a conductivity of 1.5×10-2 S/cm are obtained. These high-quality Cu2OO thin films are expected to be applied to Cu2OO-based heterojunction solar cells and optical functional films. [ABSTRACT FROM AUTHOR]

We present a vapour phase based approach for the epitaxial growth of Cu2O with the utilization of elemental copper and oxygen as precursor materials. At present the implementation of MOCVD approach is hampered by the absence of the chemical source of Cu with high enough vapour pressure at reasonable temperatures. Moreover, the use of elemental precursors has the advantage of less impurity incorporation during growth opposed to chemical vapour based growth methods. The influence of process parameters on the growth is discussed. High resolution X-ray diffraction measurements reveal the growth of mainly the two (002) and (220) Cu2O orientations. Precise control of the growth parameters provides the reproducible growth of pure Cu2O phase without additional CuO formation. Epitaxial growth of Cu2O is demonstrated on a-plane Al2O3 in the temperature range of 730 °C-870 °C. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

We present a vapour phase based approach for the epitaxial growth of Cu2O with the utilization of elemental copper and oxygen as precursor materials. At present the implementation of MOCVD approach is hampered by the absence of the chemical source of Cu with high enough vapour pressure at reasonable temperatures. Moreover, the use of elemental precursors has the advantage of less impurity incorporation during growth opposed to chemical vapour based growth methods. The influence of process parameters on the growth is discussed. High resolution X-ray diffraction measurements reveal the growth of mainly the two (002) and (220) Cu2O orientations. Precise control of the growth parameters provides the reproducible growth of pure Cu2O phase without additional CuO formation. Epitaxial growth of Cu2O is demonstrated on a-plane Al2O3 in the temperature range of 730 °C-870 °C. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]