Role Of Cu Research Articles

Decorating Cu2O with Copper Metal (Cu) through Facile Electrochemical Deposition for Methylene Blue Degradation

Cuprous oxide (Cu2O) thin film was decorated with copper metal (Cu) by the simple electrochemical deposition method. This study was motivated to improve the role of Cu as a co-catalyst due to the narrow band gap energy of known photocatalyst Cu2O. Cu was electrodeposited on Cu2O thin film with a substrate of indium tin oxide (ITO) at a voltage of -0.3V and a temperature of 60 °C in CuSO4 (pH 10) under a magnetic stirrer. The structure, phase, and morphology of Cu2O/Cu were characterised by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The electrocatalytic performance of Cu2O/Cu was recorded using linear sweep voltammetry and electrochemical impedance spectroscopy. XRD and SEM results show Cu was successfully deposited covering Cu2O. The current density of Cu2O/Cu increased by 2.7041 mA/cm2 confirming the lower charge current resistance of 2.48 kΩ. The Cu-decorated Cu2O demonstrated an improved photocatalytic activity, as shown by the increase of MB degradation from 46.33% to 50.87%. It was believed from characterisations that Cu deposition leads to more dense carriers and charge transfer, hence higher photocatalytic activity towards MB degradation than bare Cu2O thin film.

Copper single atoms decorated iridium nanoparticles for the selective hydrogenation of bromonitrobenzene

The interaction between metals is an important factor to modify the catalytic roles of metallic catalysts, and it is highly desirable to reveal the relationship between metal-metal interaction and catalytic performance. Three types of Ir-Cu catalysts including Cu single atoms modified Ir nanoparticles and Ir-Cu alloy catalysts are prepared to observe the modifying role of Cu on Ir. Under relatively high temperature treatment, Ir-Cu alloy can be produced from Cu single atoms and Ir nanoparticles. The selectivity to bromoaniline (BAN) over Cu/C-Ir catalyst can be up to 99.9 % at the 100 % conversion of bromonitrobenzene (BNB), which is higher than that over Ir/C (94.3 %) and Ir-Cu/C alloy catalyst (98.5 %). The turnover frequencies (TOFs) of Cu/C-Ir catalysts are evidently lower than that of the Ir-Cu/C alloy catalyst, though their dispersions are higher than that of Ir-Cu/C alloy catalyst. The electronic transfer from Cu single atoms to Ir nanoparticles not only weakens the hydrogen adsorption ability but reduces the number of active sites available for splitting hydrogen molecules into hydrogen atoms, leading to a decrease in the catalytic activity for the selective hydrogenation of BNB. The interaction exerted by unalloyed Cu single atoms on Ir nanoparticles differs from that of alloyed Cu on Ir, which may be the possible reason for the different catalytic performance between Cu single atoms modified Ir nanoparticles and Ir-Cu alloy.

Emerging perspectives of copper-mediated transcriptional regulation in mammalian cell development.

Copper (Cu) is a vital micronutrient necessary for proper development and function of mammalian cells and tissues. Cu mediates the function of redox active enzymes that facilitate metabolic processes and signaling pathways. Cu levels are tightly regulated by a network of Cu-binding transporters, chaperones, and small molecule ligands. Extensive research has focused on the mammalian Cu homeostasis (cuprostasis) network and pathologies, which result from mutations and perturbations. There are roles for Cu-binding proteins as transcription factors (Cu-TFs) and regulators that mediate metal homeostasis through the activation or repression of genes associated with Cu handling. Emerging evidence suggests that Cu and some Cu-TFs may be involved in the regulation of targets related to development-expanding the biological roles of Cu-binding proteins. Cu and Cu-TFs are implicated in embryonic and tissue-specific development alongside the mediation of the cellular response to oxidative stress and hypoxia. Cu-TFs are also involved in the regulation of targets implicated in neurological disorders, providing new biomarkers and therapeutic targets for diseases such as Parkinson's disease, prion disease, and Friedreich's ataxia. This review provides a critical analysis of the current understanding of the role of Cu and cuproproteins in transcriptional regulation.

Pyrite activation in seawater flotation by copper and lead ions: XPS and in-situ electrochemical investigation

Pyrite, as the main carrier of gold, can be collected via flotation which consumes high volumes of fresh water. Seawater is the promising alternative to fresh water, especially in the fresh water deficient regions. However, pyrite flotation is usually ineffective in seawater, which requires activation prior to recovery. This study mainly focuses on the roles of Cu2+ and Pb2+ on pyrite flotation in seawater. The flotation and contact angle results indicated that Cu2+ and Pb2+ obviously increased pyrite recovery in seawater by enhancing its surface hydrophobicity. Further XPS studies revealed that the formation of Fe-S-Cu(I) and Fe-O-Cu(II) on pyrite surface due to Cu2+ activation while the presence of Fe-O-Pb(II) and Fe-SO-Pb(II) due to Pb2+ activation, thereby improving the active sites and adsorption of xanthate. In addition, the in-situ scanning electrochemical microscopy (SECM) results showed that the formation of Cu2+ and Pb2+ activated products increased the electrochemical reactivity of pyrite surface, which was the main reason for the improved pyrite floatability. Moreover, the current consequence evolution indicated that pyrite activation by Cu2+ was stronger than that by Pb2+. The SECM imaging also showed that the adsorption of xanthate decreased the electrochemical reactivity on pyrite surface, with more significant role observing on the activated surface than that of the un-activated pyrite. It should be noted that the Cu2+/Pb2+ activation and xanthate adsorption were distributed unevenly on pyrite surface. This study therefore provides an in-situ approach to understand the role of inorganic ions and reagents on pyrite flotation in seawater, providing a promising strategy to use seawater for the flotation recovery of gold.

Structural Expansion and Enhanced Photocurrent Conversion of Selenido Stannates with Cu+ Ions.

As a means of tuning the electronic properties of tin-chalcogenide-based compounds, we present a strategy for the compositional and structural expansion of selenido stannate frameworks under mild conditions by introducing Cu+ ions into binary anionic Sn/Se aggregates in ionothermal reactions. The variable coordination modes of Cu+-contrasting with tetrahedral {SnSe4} or trigonal bipyramidal {SnSe5} units-and corresponding expansion toward ternary Cu/Sn/Se substructures helped to add another degree of freedom to the nanoarchitectures. As desired, the variation of the structural features was accompanied by concomitant changes of the physical properties. Upon treatment of alkali metal salts of the [SnSe4]4- anion at slightly elevated temperatures (120 or 150 °C) in ionic liquids, we isolated a series of compounds comprising ternary or quaternary cluster molecules or networks of cluster units, (C2C2Im)9Li[Cu10Sn6Se22] (1), (C2C2Im)4[Cu8Sn6Se18] (2), (C2C1Im)3[Cu5Sn3Se10] (3), and (C2C2Im)5[Cu8Sn6Se18F]·(C2C2Im)[BF4] (4; C2C2Im = 1,3-diethyl-imidazolium, C2C1Im = 1-ethyl-3-methyl-imidazolium), which were investigated in terms of their optical gaps and photocurrent conversion properties. As illustrated by the synthesis and characterization of an additional salt that does not include Cu+, {(C2C2Im)2[Sn3Se7]}4·{(C2C2Im)[BF4]}2 (5), the significant role of Cu+ in this system was shown to be 3-fold: (a) structural expansion, (b) narrowing of the optical gap, and (c) photocurrent enhancement. By this three-in-one effect, the work offers an in-depth understanding of chalcogenido metalate chemistry with atomic precision.

Boosting peroxymonosulfate activation via Fe–Cu bimetallic hollow nanoreactor derived from copper smelting slag for efficient degradation of organics: The dual role of Cu

Valorization of iron-rich metallurgical slags in the construction of Fenton-like catalysts has an appealing potential from the perspective of sustainable development. For the first time, copper smelting slag (CSS) was utilized as the precursor to synthesize hollow sea urchin-like Fe–Cu nanoreactors (Cu1.5Fe1Si) to activate peroxymonosulfate (PMS) for chlortetracycline hydrochloride (CTC) degradation. The hyper-channels and nano-sized cavities were formed in the catalysts owing to the induction and modification of Cu, not only promoting the in-situ growth of silicates and the formation of cavities due to the etching of SiO2 microspheres, but also resulting the generation of nanotubes through the distortion and rotation of the nanosheets. It was found that 100 % CTC degradation rate can be achieved within 10 min for Cu1.5Fe1Si, 75 times higher than that of Cu0Fe1Si (0.0024 up to 0.18 M−1‧min−1). The unique nanoconfined microenvironment structure could enrich reactants in the catalyst cavities, prolong the residence time of molecules, and increase the utilization efficiency of active species. Density functional theory (DFT) calculations show that Cu1.5Fe1Si has strong adsorption energy and excellent electron transport capacity for PMS, and Fe-Fe sites are mainly responsible for the activation of PMS, while Cu assists in accelerating the Fe(II)/Fe(Ⅲ) cycle and promotes the catalytic efficiency. The excellent mineralization rate (83.32 % within 10 min) and efficient treatment of CTC in consecutive trials corroborated the high activity and stability of the Cu1.5Fe1Si. This work provides a new idea for the rational design of solid waste-based eco-friendly functional materials, aiming at consolidating their practical application in advanced wastewater treatment.

MAMMALIAN COPPER HOMEOSTASIS: PHYSIOLOGIC ROLES AND MOLECULAR MECHANISMS.

In the past decade, evidence for numerous roles of copper (Cu) in mammalian physiology has grown exponentially. The discoveries of Cu involvement in cell signaling, autophagy, cell motility, differentiation, and regulated cell death (cuproptosis) have markedly extended the list of already known functions of Cu, such as a cofactor of essential metabolic enzymes, a protein structural component, and a regulator of protein trafficking. Novel and unexpected functions of Cu transporting proteins and enzymes have been identified, and new disorders of Cu homeostasis have been described. Significant progress has been made in the mechanistic studies of two classic disorders of Cu metabolism, Menkes disease and Wilson disease, which paved ways to novel approaches to their treatment. Discovery of cuproptosis and the role of Cu in cells metastatic growth have markedly increased interest in targeting Cu homeostatic pathways to treat cancer. In this review, we summarize the established concepts in the field of mammalian Cu physiology, and discuss how new discoveries of the past decade expand and modify these concepts. The roles of Cu in brain metabolism, in cells' functional speciation and a recently discovered regulated cell death have attracted significant attention and are highlighted in this review.

Unveiling role of Cu(II) in photochemical transformation and reactive oxygen species production of schwertmannite in the presence of tartaric acid

Unveiling role of Cu(II) in photochemical transformation and reactive oxygen species production of schwertmannite in the presence of tartaric acid

First-Principles Study on the Role of Cu and Cl-Based Dopants in NiO

First-Principles Study on the Role of Cu and Cl-Based Dopants in NiO

In-situ complexation of Cu(II) with polyethyleneimine (PEI) triggers the enhanced formation of halonitromethanes, dichloroacetonitrile, and dichloroacetamide during UV/chlorine disinfection: Cu(I) contribution and Cl· sustainable production

The complexation of copper ions (Cu(II)) with coexisting organic ligands (e.g. polyethyleneimine (PEI)) in water may pose a new threat to water quality. This study revealed that the maxima concentrations of HNMs, DCAN, and DCAcAm from Cu(II)-PEI complex during UV/chlorine disinfection were 1.54, 2.00, and 1.25 times higher than those from PEI, and the maxima concentrations of HNMs, DCAN, and DCAcAm from Cu(II)-PEI complex during chlorination disinfection were 1.22, 1.31, and 1.10 times higher than those from PEI. Meanwhile, specific Cu(II) concentration (0.25 ∼ 3.0 mg L−1) and alkaline pH were more favorable for forming HNMs, DCAN, and DCAcAm during UV/chlorine disinfection, which were highly dependent on the involvement of HO· and Cl·. Cu(II)-PEI, an in-situ formed stable complex that permitted an efficient interconversion cycle of Cu(II)/Cu(I) via concurrent metal-to-ligand charge transfer and ligand-to-metal charge transfer. The analysis and comparison of extensive products provided solid evidence for the primary role of Cu(I) and the enhanced production of Cl· in increasing HNMs, DCAN, and DCAcAm productions, rather than only Cu(II) catalysis similar to that during chlorination. The new findings broaden the knowledge of the influence of in-situ formed Cu(II)-organic complexes on forming HNMs, DCAN, and DCAcAm during UV/chlorine disinfection.

Unraveling the potential of Cu addition and cluster hardening in Al-Mg-Si alloys

With the aim of further exploiting the trade-off between formability and strength in Al alloys, this study addresses the influence of Cu in Al-Mg-Si alloys that achieve simultaneously high strength and high ductility via cluster hardening. The study carefully examines the mechanical properties and strain hardening behavior of various Mg/Si ratios with and without Cu and compares the effects of pre-aging and atypical long-term low-temperature aging treatments at 100°C to conventional heat treatments. Interestingly, in all cases adding Cu improved ductility. In the extremal case cluster hardening plus the addition of Cu quadruples elongation, while keeping yield strength similar to the classical T6 state. The results of the study are discussed with a focus on the dense distribution of clusters and partial hardening phases based on atom probe tomography data. Most importantly, the cluster-hardened alloys exhibit pronounced strain-hardening properties, which we evaluate using a Kocks-Mecking approach in combination with a microstructural analysis in the pre-aging and long-term aging condition. The key finding of the study involves the role of Cu in refining clusters/precipitates, where it causes a substantial increase in number density and volume fraction. This refinement, in combination with strain-induced clustering, contributes significantly to improving the alloys’ overall mechanical performance and underlines the central role of Cu in tailoring microstructural features, especially in alloys primarily strengthened by clusters.

Absence of lung tumor promotion with reduced tumor size in mice after inhalation of copper welding fumes.

Welding fumes are a Group 1 (carcinogenic to humans) carcinogen as classified by the International Agency for Research on Cancer. The process of welding creates inhalable fumes rich in iron (Fe) that may also contain known carcinogenic metals such as chromium (Cr) and nickel (Ni). Epidemiological evidence has shown that both mild steel (Fe-rich) and stainless steel (Fe-rich + Cr + Ni) welding fume exposure increases lung cancer risk, and experimental animal data support these findings. Copper-nickel (CuNi) welding processes have not been investigated in the context of lung cancer. Cu is intriguing, however, given the role of Cu in carcinogenesis and cancer therapeutics. This study examines the potential for a CuNi fume to induce mechanistic key characteristics of carcinogenesis in vitro and to promote lung tumorigenesis, using a two-stage mouse bioassay, in vivo. Male A/J mice, initiated with 3-methylcholanthrene (MCA; 10 µg/g), were exposed to CuNi fumes or air by whole-body inhalation for 9 weeks (low deposition-LD and high deposition-HD) and then sacrificed at 30 weeks. In BEAS-2B cells, the CuNi fume-induced micronuclei and caused DNA damage as measured by γ-H2AX. The fume exhibited high reactivity and a dose-response in cytotoxicity and oxidative stress. In vivo, MCA/CuNi HD and LD significantly decreased lung tumor size and adenomas. MCA/CuNi HD exposure significantly decreased gross-evaluated tumor number. In summary, the CuNi fume in vitro exhibited characteristics of a carcinogen, but in vivo, the exposure resulted in smaller tumors, fewer adenomas, less hyperplasia severity, and with HD exposure, less overall lung lesions/tumors.

Tracking the critical roles of Cu+ and Cu0 sites and the optimal Cu+/Cu0 ratio for CH3OH steam reforming (MTSR) to manufacture H2

Understanding the nature of surface-active sites is of critical importance for catalyst design, yet remains great challenges because of the complexity of solid surfaces. To tracking the valence states and roles of various Cu sites played in CH3OH steam reforming (MTSR) on Cu-based catalysts and the factors to determine the reactivity, appropriate Cu/Ce1-xZrxO2 solid solution catalysts have been purposely designed. On a catalyst having a Ce/Zr ratio of 0.7/0.3 (Cu/Ce0.7Zr0.3O2), the optimal Cu+/Cu0 ratio around 1.00 can be obtained to accomplish the best performance, with a high H2 production rate but very low CO selectivity. With the combination of experiments and DFT calculation, it has been discovered that CH3OH molecules mainly be adsorbed/activated on the Cu+ sites, but H2O molecules could mainly be adsorbed/activated on the Cu0 sites. We have substantiated that to fabricate Cu/Ce1-xZrxO2 catalysts with high efficiency, nearly equal amount of surface Cu+ and Cu0 sites should be engineered.

Oxidizing Role of Cu Cocatalysts in Unassisted Photocatalytic CO2 Reduction Using p-GaN/Al2O3/Au/Cu Heterostructures.

Photocatalytic CO2 reduction to CO under unassisted (unbiased) conditions was recently demonstrated using heterostructure catalysts that combine p-type GaN with plasmonic Au nanoparticles and Cu nanoparticles as cocatalysts (p-GaN/Al2O3/Au/Cu). Here, we investigate the mechanistic role of Cu in p-GaN/Al2O3/Au/Cu under unassisted photocatalytic operating conditions using Cu K-edge X-ray absorption spectroscopy and first-principles calculations. Upon exposure to gas-phase CO2 and H2O vapor reaction conditions, the composition of the Cu nanoparticles is identified as a mixture of CuI and CuII oxide, hydroxide, and carbonate compounds without metallic Cu. These composition changes, indicating oxidative conditions, are rationalized by bulk Pourbaix thermodynamics. Under photocatalytic operating conditions with visible light excitation of the plasmonic Au nanoparticles, further oxidation of CuI to CuII is observed, indicating light-driven hole transfer from Au-to-Cu. This observation is supported by the calculated band alignments of the oxidized Cu compositions with plasmonic Au particles, where light-driven hole transfer from Au-to-Cu is found to be thermodynamically favored. These findings demonstrate that under unassisted (unbiased) gas-phase reaction conditions, Cu is found in carbonate-rich oxidized compositions rather than metallic Cu. These species then act as the active cocatalyst and play an oxidative rather than a reductive role in catalysis when coupled with plasmonic Au particles for light absorption, possibly opening an additional channel for water oxidation in this system.

Direct evidence from STXM analysis of enhanced oxygen storage capacity in ceria through the addition of Cu and Mg: Correlation of HT-WGS reaction performance

Here, scanning transmission X-ray microscopy (STXM) analysis was utilized to directly present visual evidence of changes in oxygen storage capacity (OSC) when small amounts of an additive were incorporated into CeO2. Specifically, the chemical map measured by STXM analysis differentiated between Cu-rich and Ce-rich areas to derive the proportion of Ce3+. Additionally, we found that the dispersion of Cu significantly influenced the formation of OSC. The findings were applied to the high-temperature water–gas shift reaction for producing high-purity hydrogen from waste-derived syngas, establishing a correlation with catalyst performance. Consequently, the CCM75 (Ce/Mg = 75/25) catalyst demonstrated the highest Cu dispersion and OSC values (6.9 %, 800.3 μmolO/gcat), and it also showed the highest CO conversion (79 % at 450 °C) and stability (−7.7 % at 450 °C after 50 h), attributed to the significant presence of active Cu. This study confirms previously reported interactions between Cu and CeO2 and uncovers the significant roles of Cu and Mg in this catalysis system, providing new understanding of the mechanisms that facilitate OSC improvement.

Ultra-efficient peroxymonosulfate utilization and trichloroethylene degradation in heterogeneous catalytic system guided by sheet-like Cu2MnO4 nanoparticles: The role of Cu(III)–O species and free radicals

Synthesizing cubic spinel Cu2MnO4 with nanosheet structure (SCMO) aimed to construct a “non-radical-mediated radical-oxidative reaction”, for increasing PMS utilization efficiency, and solving the defects of SO4•− and •OH through indirect PMS activation by electron transfer process. Compared with box-like Cu2MnO4 (11.1%, 0.0035 min−1) and ordinary Cu2MnO4 nanoparticles (21.3%, 0.0070 min−1), SCMO/PMS showed excellent trichloroethylene removal (98.8%, 0.1577 min−1). The pivotal role of Cu(III) was determined based on EPR analysis, quenching experiments, chemical probe experiments, hydrogen temperature-programmed reduction and Raman spectroscopy analysis, in-situ FTIR and Raman analyses. In brief, the interaction between PMS and SCMO could produce surface-bonded reactive complexes and the subsequent breaking of O–O bond in the sub-stable structure allowed the conversion of Cu(II) to Cu(III), which in turn facilitates the generation of •OH and SO4•−. The density functional theory (DFT) calculations provided supporting evidence for the electron donor role of SCMO and the increase of the electron acceptance capacity of PMS. SCMO/PMS system showed good resistance and degradation efficiency to complex composition and combined pollutants in actually contaminated groundwater, respectively. However, the coexistence of high concentrations of arsenic could significantly affect SCMO performance due to their adsorption on –OH groups, which still need in-depth study.

Construction of porous Cu/CeO2 catalyst with abundant interfacial sites for effective methanol steam reforming

Methanol is a promising hydrogen carrier for fuel cell vehicles (FCVs) via methanol steam reforming (MSR) reaction. Ceria supported copper catalyst has attracted extensive attentions due to the extraordinary oxygen storage capacity and abundant oxygen vacancies. Herein, we developed a colloidal solution combustion (CSC) method to synthesize a porous Cu/CeO2(CSC) catalyst. Compared with Cu/CeO2 catalysts prepared by other methods, the Cu/CeO2(CSC) catalyst possesses highly dispersed copper species and abundant Cu+-Ov-Ce3+ sites at the copper-ceria interface, contributing to methanol conversion of 66.3 %, CO2 selectivity of 99.2 %, and outstanding hydrogen production rate of 490 mmol gcat−1 h−1 under 250 °C. The linear correlation between TOF values and Cu+-Ov-Ce3+ sites amount indicates the vital role of Cu+-Ov-Ce3+ sites in MSR reaction, presenting efficient ability in activation of water. Subsequently, a deep understanding of CSC method is further presented. In addition to serving as a hard template, the colloidal silica also acts as disperser between nanoparticles, enhancing the copper-ceria interactions and facilitating the generation of Cu+-Ov-Ce3+ sites. This study offers an alternative approach to synthesize highly dispersed supported copper catalysts.

Critical Role of Cu Nanoparticle-Loaded Cu(100) Surface Structures on Structured Copper-Based Catalysts in Boosting Ethanol Generation in CO2 Electroreduction.

Presently, realizing high ethanol selectivity in CO2 electroreduction remains challenging due to difficult C-C coupling and fierce product competition. In this work, we report an innovative approach for improving the efficiency of Cu-based electrocatalysts in ethanol generation from electrocatalytic CO2 reduction using a crystal plane modification strategy. These novel Cu-based electrocatalysts were fabricated by electrochemically activating three-dimensional (3D) flower-like CuO micro/nanostructures grown in situ on copper foils and modifying with surfactants. It was demonstrated that the fabricated Cu-based electrocatalyst featured a predominantly exposed Cu(100) surface loaded with high-density Cu nanoparticles (NPs). The optimal Cu-based electrocatalyst displayed considerably improved CO2 electroreduction performance, with a Faraday efficiency of 37.9% for ethanol and a maximum Faraday efficiency of 68.0% for C2+ products at -1.4 V vs RHE in an H-cell, accompanied by a high current density of 69.9 mA·cm-2, much better than the particulate Cu-based electrocatalyst. It was unveiled that the Cu(100)-rich surface of nanoscale petals with abundant under-coordinated copper atoms from CuNPs was conducive to the formation and stabilization of key *CH3CHO and *OC2H5 intermediates, thereby promoting ethanol generation. This study highlighted the critical role of CuNP-loaded Cu(100) surface structures on structured Cu-based electrocatalysts in enhancing ethanol production for the CO2 electroreduction process.

Mechanistic insights into δ-MnO2/biochar–activated persulfate-treated wastewater containing antibiotics and heavy metals: Nonradical pathway and pivotal role of Cu(Ⅱ) at low temperature

Herein, we present a high efficiency system based on biochar loaded with layered manganese dioxide to remove tetracycline and heavy metals from livestock wastewater. Under the optimal conditions, the degradation efficiencies of TC in the δ-MnO2/BC/PS system were 85.5% at 25 °C and 38.5% at 5 °C. Radical quenching experiments revealed that radical reactions in the δ-MnO2/BC/PS system were weak under 15 °C. Adsorption degradation experiments showed that the system maintained good adsorption performance at 5 °C. Galvanic cell experiments and cyclic voltammetry showed that the δ-MnO2/BC material had good electrochemical activity and high stability in response to temperature, indicating that TC was degraded by a nonradical pathway that was not limited by temperature, such as electron transfer. Copper ion was important coadsorbent and coactivator of the reaction system. Furthermore, FTIR, XPS, and X-ray diffraction (XRD) analyses showed that Cu(II) in the system was involved in changing the manganese valence state in the δ-MnO2/BC material and increasing the –OH content of BC. Comparison of the different products generated during metabolic testing revealed that the reaction pathway of the system at low temperature (5 °C) differed from that at normal temperature (25 °C). The δ-MnO2/BC material demonstrated good removal ability for antibiotics and heavy metals at normal and low temperatures in actual biogas slurry. The study provides insight for improving the efficiency of environmentally friendly treatments of aquaculture wastewater in cold regions, which is of great significance for resource utilization.

The role of Cu and film thickness on the photocatalytic activity of mesoporous spin coated TiO2 films

Most practical applications of photocatalysts will involve coatings on an inert support; here we have examined how copper doping of spin coated porous TiO2 films affects their physical characteristics and photocatalytic activity. The photocatalytic degradation of stearic acid was used as a measure of photocatalytic activity for catalysts spin coated from a sol-gel onto glass with 0, 0.1, 0.5, 1, 2.5 and 5 wt% copper introduced into the catalyst lattice before gelation. The effects of spin coating speed on film thickness, structure and band gap were studied and the nature of the copper incorporated into the films examined with XPS and XANES measurements. Increased spin coating speeds reduces the thickness of the deposited films from ∼ 50 μm to ∼ 20 μm until a spin speed of ∼ 3000 rpm at which point non-Newtonian behaviour of the gels prevents further reductions in film thickness. A larger effect on film thickness is the presence of the added copper nitrate which results in thinner films. After calcining, XANES shows the bulk of the copper to be in a Cu(II) state but at the surface of the thinnest, most active films XPS shows only Cu(I). Photocatalytic activity is much more strongly affected by the presence of the copper than the thickness of the films with 0.1 wt% Cu catalysts as much as 10 times more active than the undoped catalysts. Increasing the copper content, however, reduces activity until at ∼ 5 wt% activity is lower than for the pure TiO2 films.