Bare Co3O4 Research Articles

S‐Scheme MnO2/Co3O4 Sugar‐Gourd Nanohybrids with Abundant Oxygen Vacancies for Efficient Visible‐Light‐Driven CO2 Reduction

AbstractConverting CO2 to carbon‐based fuels using solar energy via photocatalysis is a promising approach to boost carbon neutrality. However, the solar‐to‐chemical conversion efficiency is hampered by interconnected multiple factors including insufficient light absorption, low separation efficiency of photogenerated carriers as well as complex and sluggish surface reaction kinetics. Herein, we incorporate MnO2 nanowires and Co3O4 hollow polyhedrons with abundant oxygen vacancies (VO) into MnO2/Co3O4 sugar‐gourd nanohybrids for boosting CO2 photoreduction. The MnO2/Co3O4 nanohybrids not only display strong absorption in the visible–near infrared region, but also facilitate the separation of photogenerated carriers in terms of S‐scheme transfer pathway, supplying abundant electrons for CO2 reduction reaction. Furthermore, the presence of VO enhances the separation efficiency of photogenerated carriers and promotes the chemical adsorption to CO2 molecules. In addition, the interfacial electronic interaction between MnO2 and Co3O4 also contributes to the chemical adsorption and activation to CO2. Owing to the synergy of S‐scheme transfer pathway and VO, the MnO2/Co3O4 hybrids exhibit greatly enhanced photocatalytic activity towards CO2 reduction under the irradiation of visible light in comparison with bare MnO2 and Co3O4, delivering a CO evolution rate of 15.9 umol g−1 h−1 with a 100 % selectivity.

N2O Decomposition on Singly and Doubly (K and Li)-Doped Co3O4 Nanocubes─Establishing Key Factors Governing Redox Behavior of Catalysts.

The intimate mechanism of N2O decomposition on bare and redox-tuned Co3O4 nanocubes (achieved by single (Li or K) and double (Li and K) doping) was elucidated. The catalysts synthesized by the hydrothermal method were characterized by X-ray electron absorption fine structure measurements, X-ray diffraction, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, and Kelvin Probe techniques. TPSR and steady-state isothermal catalytic tests reveal that the N2O turnover frequencies are critically sensitive to the work function of the catalysts, adjusted purposely by doping. For the catalysts obtained by one-pot hydrothermal synthesis, lithiation of the Co3O4 nanocubes leads to the formation of {Li'8a, Co·16d} species, decreasing steadily the work function and the activity, while for the catalysts prepared by postsynthesis impregnation, formation of {Li'8a, Co'16d, Co··16c} species leads to a volcano-type dependence of the catalytic activity and the work function in parallel. The beneficial effect of potassium was discussed in terms of mitigation of surface potential buildup due to the accumulation of ionosorbed oxygen intermediates (surface electrostatics), which hinders the interfacial electron transfer. Analysis of the catalytic activity response to the redox tuning of Co3O4, substantiated by DFT calculations, allowed for a straightforward conceptualization of the redox nature of the N2O decomposition in terms of the lineup of frontier orbitals of the N2O/N2O- and O2-/O2 reactants with the surface DOS structure and the resultant molecular orbital interactions. The positions of the virtual bonding 3πg0(N2O)-α-3dz2 and the occupied 2πg1(O2-)-α-3dz2 states relative to the Fermi energy level play a crucial role in the regulation of the forward and backward interfacial electron transfer events, which drive the redox process.

Biomimetic mineralization synthesis of tricobalt tetraoxide/nitrogen doped carbon skeleton for enhanced capacitive deionization

Developing novel capacitive deionization (CDI) electrode materials with high salt adsorption capacity and adsorption rate is essential for desalination applications, however, encountering significant challenges. Herein, a facile and energy economical biomimetic mineralization method is proposed to construct the tricobalt tetraoxide/nitrogen doped carbon (Co3O4/NC) heterostructure. Benefiting from the mild biomimetic mineralization process, small Co3O4 nanoparticles grow uniformly on interconnected multi-branched NC skeleton. The as-obtained Co3O4/NC heterostructure exhibits a salt adsorption capacity of 44.5 mg g−1, adsorption rate of 7.9 mg g−1 min−1, and 91.3 % of capacity retention after 60 cycles at 1.2 V in 500 mg L−1 salt solution. These performances overwhelm the bare Co3O4 (24.6 mg g−1, 3.5 mg g−1 min−1, 65.7 %), indicating superior desalination performances of the Co3O4/NC heterostructure. This study gives an insight into the biomimetic mineralization method and provides one promising candidate of CDI electrode.

Design of highly stable Co3O4/RGO/CoFe2O4 hybrid nanocomposites with multiple nanointerfaces for enhanced supercapacitor performance

In this study, we developed a novel hybrid electrode nanomaterial composed of Co3O4, CoFe2O4, and reduced graphene oxide (RGO) for electrochemical supercapacitor applications. The hybrid nanocomposite of Co3O4/RGO/CoFe2O4 was prepared using a modified chemical oxidation process and the phase formation of the composites was evidenced by X-ray diffraction (XRD). The grain size for Co3O4 and CoFe2O4 was estimated as 12 nm and 22 nm. For Co3O4/CoFe2O4 the reduced grain size of 19 nm for CoFe2O4 was observed and further it was reduced with RGO up to 15 nm. The bare Co3O4 exhibited a hexagonal plate-like morphology, whereas the bare CoFe2O4 showed mostly a spherical morphology. The reduced saturation magnetization for the hybrid electrode material due to the non-magnetic fraction of Co3O4 and RGO was observed to be 21 emu/g compared to the bare CoFe2O4 (77 emu/g). The Co3O4/RGO/CoFe2O4 electrode exhibited enriched electroactive sites and enhanced diffusion pathways, achieving a high specific capacity of 235C g − 1 at 5 A g − 1 with excellent durability.. This work highlights the significant charge storage potential of the Co3O4/RGO/CoFe2O4 hybrid, making it a promising candidate for advanced energy storage systems.

Bismuth sulfide-impregnated cobalt oxide nanocrystals: An enhanced photocatalyst for improved hydrogen production beneath visible light

Hydrogen (H2) is the lightest and greenest fuel compared to conventional energy resources. The production of H2 could be achieved via several techniques as renewable energy sources. Due to its simplicity, the visible-light H2 evolution over nanocomposite photocatalysts is an emerging method. Following this, the surfactant-aided sol–gel way has grown Cobalt oxide (Co3O4) nanoparticles. 3.0–12.0 wt% of bismuth sulfide (Bi2S3) nanocrystals were added to Co3O4 by impregnating technique to enhance the visible-light photoactivity. The produced nanostructures were utilized to generate H2 by photocatalytic reaction in a water/glycerol medium with platinum traces cocatalyst. The impregnation of Bi2S3 at 9.0 wt% has endorsed the photogenerated H2 by ∼ 8.7 folds (∼1547 µmol g−1 h−1) than only using bare Co3O4 (∼178 µmol g−1 h−1) owing to bandgap reduction down to 1.71 eV and suppression of charge recombination. The dose control of 2.5 gL−1 has augmented the H2 generation to 3.095 mmol g−1 h−1 with a significant regeneration to reach 96.5 % after the fifth run. The improved performance of the formed 9.0 % Bi2S3/Co3O4 heterojunction is accredited to the enhanced photocharge separation between Bi2S3 and Co3O4.

Highly sensitive colorimetric sensing for ascorbic acid utilizing Co3O4@MnO2 hollow nanocubes as oxidase mimic

The development of oxidase mimic with favorable catalytic activity is of great significance for the rapid and convenient detection of ascorbic acid (AA). Herein, in this work, a synergistic regulation strategy of heterogeneous interface and hollow structure is proposed to effectively solve the problem of limited active sites obtained with Co3O4. The charge rearrangement at heterointerface could improve the catalytic activity of oxidase mimic. Moreover, the hollow nanocubes structure could increase specific surface area and provide rich active sites. As a result, the target material possesses enhanced oxidase-like catalytic activity and desirable stability compared to bare Co3O4 and MnO2, which also catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to form a blue product (ox-TMB) even without hydrogen peroxide. Ox-TMB is reduced to TMB owing to the strong reducibility of AA, which represents a decrease in absorbance at 652 nm and a colorless solution. Moreover, an efficient biosensing method for the detection of AA is developed. The relative absorbance (∆A) of the sensing platform is linearly related to the concentration of AA in the range of 0–200 μM, and the detection limit is 0.11 μM. This work provides a novel method for the rapid, cost-effective and sensitive detection of AA, and possesses a wide range of potential application value.

Interfacial electron interactions governed photoactivity and selectivity evolution of carbon dioxide photoreduction with spinel cobalt oxide based hollow hetero-nanocubes

In this work, an efficient CO2 photoreduction catalyst based on Co3O4/ZnIn2S4 hollow hetero-nanocubes is precisely constructed via an in-situ transformation of cobalt-organic framework followed by a solvothermal reaction. Comprehensive in-situ spectroscopic analyses and theoretical calculations have revealed that the critical interfacial electron interactions (IEIs) effects on both photoactivity evolution and selectivity modulation in the Co3O4/ZnIn2S4 hetero-structure. As the content of ZnIn2S4 increases in the hetero-structure, the photoactivity exhibits a volcano-like evolution profile but the CH4 selectivity reduces monotonously. The improved photoactivity is attributed to the IEIs-promoted charge separation as well as the specific-surface-area effect in terms of electron unitization rate, and the electronic structure of Co3O4 is tuned and the energy barrier for the key reaction intermediate *CHO is reduced, leading to improved CH4 selection in comparison with bare Co3O4. The IEIs-mediated production selectivity is further verified by a Co3O4/CeO2 heterojunction, indicating a certain universality of the IEI effect.

Superior lithium storage performance of SnO2–modified Co3O4 microflowers self–assembled with porous nanosheets as anode materials in Li–ion batteries

SnO2–modified Co3O4 microflowers self–assembled with porous nanosheets are prepared with the help of solvothermal methods and annealing treatment without using any templates, and ultra–small SnO2 particles are dispersed on the surface of the Co3O4 nanosheets. The structures and physical properties of the as–synthesized samples are characterized by XRD, FESEM, HRTEM, EDS, element mapping, ICP–AES, XPS and N2 adsorption/desorption measurement. According to the N2 adsorption–desorption isotherm curves, the samples show hierarchically porous structures, and SnO2–modified Co3O4 microflowers have a higher surface area (19.5 m2 g–1 for Co3O4; 30.5 m2 g–1 for SnO2–modified Co3O4). As anode materials in Li–ion batteries, compared with bare Co3O4 microflowers, the SnO2–modified Co3O4 sample delivers higher specific capacity, better rate capability and superior cyclic stability. The discharge capacity of the SnO2–modified Co3O4 sample can reach 767.5 mAh g–1 at 200 mA g–1 after 100 cycles. For even at 3.0 A g–1, the reversible capacity of the composite can still reach 438.8 mAh g–1 after 1000 cycles.

Carbon quantum dots/cobalt chalcogenide porous nanofibers for highly efficient electrocatalytic hydrogen evolution

Hydrogen is increasingly needed as a clean energy source with high energy density. Hydrogen evolution reaction (HER) via electrocatalysis is a viable way to produce clean hydrogen. The key to achieving active HER is to select highly-active electrocatalysts. Although Pt-based noble metal catalysts have excellent performance, they are expensive and earth-abundant. Compared to noble metals, cobalt chalcogenide has been used for efficient HER. Here, we first demonstrated a porous material based on C-dots/cobalt chalcogenide nanofibers as an effective electrocatalyst for HER. Co3O4/10 wt% C-dots nanofibers-based electrode reached an overpotential of 383 mV at the current density of 10 mA·cm−2 with Tafel slope of 93.4 mV·dec−1 in 1 M KOH, which is much better than bare Co3O4 (758 mV at 10 mA·cm−2, Tafel slope is 111.3 mV·dec−1). In addition to the excellent HER performance, the Co3O4/C-dots nanofibers performed very well in terms of stability after a 10-hour operation, and the overpotential was even reduced by 6.7%. With the further sulphuration, the Co3S4/C-dots nanofibers exhibited an overpotential of 280.2 mV at the current density of 10 mA·cm−2. This work indicates that the C-dots can be used as an efficient additive for cobalt chalcogenide based electrocatalysts.

Sn and Mn co-doping synergistically promotes the sensing properties of Co3O4 sensor for high-sensitive CO detection

In the realm of gas sensors, p-type metal oxide semiconductor (MOS) usually exhibits inherently low sensitivity toward target gases caused by the hole accumulation layer configuration, which seriously hinders its practical application. Diatomics co-doping is an efficient tactic for adjusting the characteristics of MOS related to gas-sensing due to their synergistic effect. In this work, we controllably synthesized bare Co3O4, Sn-doped Co3O4, Mn-doped Co3O4 and Sn/Mn co-doped Co3O4 nanosheets. The experimental results reveal that Sn/Mn co-doped Co3O4 sample presents porous nanosheets structure. 1 mol% Sn/Mn co-doped Co3O4 sensor presents enhanced response [(Rg-Ra)/Ra = 330 %∼40 ppm at 150 °C] toward CO compared with the bare Co3O4, 1 mol% Sn-doped Co3O4, and 1 mol% Mn-doped Co3O4 nanosheets. Besides, 1 mol% Sn/Mn co-doped Co3O4 nanosheets show a low limit of detection (500 ppb/experimental value), good stability and selectivity. We infer that the good CO-sensing properties may be ascribed to the oxygen vacancies defects generated by Sn4+ and Mn2+/Mn3+ co-doping, high Co3+ ratio, and high specific surface area. This study affords an effective co-doping strategy for enhancing the gas-sensing performances of p-type MOS.

Constructing functional thermal-insulation-layer on Co3O4 nanosphere for reinforced local-microenvironment photothermal PMS activation in pollutant degradation

Photothermal catalysis of functional materials triggered by light-irradiation to local heating approach attracts growing attention, but one key detail affecting catalytic thermodynamic process was often ignored that thermal-conductive surface of functional materials directly contacting reaction solution easily delivers heat to the reaction system, leading to weakening heating effect in the interfacial local catalytic microenvironment. Herein, a functional low-thermal-conductivity layer that Mn-coupling porous SiO2 shell layer was constructed over the Co3O4 nanospheres. Specifically, SiO2 with porous channels introduced acts as the thermal-insulation layer to prevent the heat dissipation of the photo-heating core of Co3O4. More importantly, porous channel and inserted MnOx active species could further offer an additive special reaction microenvironment over the photo-heating core of Co3O4. Additionally, the introduction of Mn and structural remodeling through tailored annealing temperature (600–800 °C) can give improved catalytic hybrids abundant valence states and interfacial effects. A series of Co@Mn/m-SiO2 catalysts were fabricated based on the above control tactic. The Co@Mn/m-SiO2 catalysts exhibit superior activating ability for peroxymonosulfate (PMS) to degrade bisphenol A (BPA) and other pollutants including 2, 4-dichlorophenol (2, 4-DCP), phenol (PhOH), oxytetracycline (OTC), and tetracycline (TCN). Specifically, Co@Mn/m-SiO2-700 was shown to achieve complete degradation of 20 ppm BPA in less than 10 min under optimal conditions. In addition, we demonstrated that functional silica layer modified Co3O4 affords a better photo-heating effect compared to bare Co3O4 sphere in air or water, thereby contributing to a faster PMS activation efficiency. Besides, thermal treatment processing for Co@Mn/m-SiO2 catalyst makes the surface reactive species be optimized to generate more beneficial redox pairs and reach excellent photothermal catalytic efficiency in various pollutants treatment.

Copper-induced formation of heterostructured Co3O4/CuO hollow nanospheres towards greatly enhanced lithium storage performance

We report a facile template-free fabrication of heterostructured Co3O4/CuO hollow nanospheres using pre-synthesized Co/Cu-glycerate as conformal precursor. The introduction of copper nitrate in the solvothermal reaction system of glycerol/isopropanol/cobalt nitrate readily induces the conversion from solid Co-glycerate to hollow Co/Cu-glycerate nanospheres, and the effect of the Co/Cu atomic ratio on the structure evolution of the metal glycerates as well as their corresponding oxides were investigated. When examined as anode materials for lithium-ion batteries, the well-defined Co3O4/CuO hollow nanospheres with Co/Cu molar ratio of 2.0 demonstrate excellent lithium storage performance, delivering a high reversible capacity of 930 mAh/g after 300 cycles at a current density of 0.5 A/g and a stable capacity of 650 mAh/g after 500 cycles even at a higher current density of 2.0 A/g, which are much better than their counterparts of bare CuO and Co3O4. The enhanced lithium storage performance can be attributed to the synergistic effect of the CuO and Co3O4 heterostructure with hollow spherical morphology, which greatly enhances the charge/electrolyte transfer and effectively buffers the volume changes upon lithiation/delithiation cycling.

Enhanced peroxymonosulfate activation by Co-bHAP catalyst for efficient degradation of sulfamethoxazole

The abuse of antibiotics has drawn wide attention owing to their potential risk in human health and ecosystem. As one of the most commonly used sulfonamide antibiotics, sulfamethoxazole (SMX) can hardly be removed by conventional wastewater treatment methods, and thus it has become one of the most frequently detected antibiotics in water environment. In this study, a new cobalt-based heterogeneous catalyst (Co-bHAP) was successfully prepared using the simple impregnation method with animal bone-derived hydroxyapatite (bHAP) as the support, and applied to activate peroxymonosulfate (PMS) for the degradation of SMX in water. The physicochemical properties of Co-bHAP catalyst were investigated by series of characterization methods, and the results showed that this catalyst has a rough and porous morphological structure, as well as homogeneously distributed active component, which is mainly in the form of Co3O4. The developed Co-bHAP can provide abundant reaction active sites and exhibit excellent catalytic activity and stability in PMS activation. The kinetic constant of Co-bHAP activating PMS to degrade SMX is up to 0.1524 min−1, which is 4.5 times larger than that of bare Co3O4. The SMX (20 mg/L) degradation efficiency within 30 min in Co-bHAP/PMS system reached as high as 98.7% and still maintained at 86% after 5 times consecutive operation, with slight cobalt ions leaching less than 0.1 mg/L. Based on radical quenching experiment, electron paramagnetic resonance (EPR) test and XPS analysis, the reaction mechanism was proposed. The balance among Co3+/Co2+, O2−/O2 and PMS decomposition in Co-bHAP/PMS system ensured the continuous generation of sulfate radical (SO4•–) and hydroxyl radical (HO•), both of which are responsible for SMX degradation, while SO4•– plays a leading role. In addition, four possible pathways of SMX degradation were proposed according to the eight detected intermediate products. All the results suggested that this catalyst could have a promising potential in activating PMS to degrade sulfonamide antibiotic pollutants in water.

Fabrication and electrochemical evaluation of polyhedral PANI‐coated Co3O4 electrode for supercapacitor application

AbstractIn this work, conducting polymer modification on metal oxide surfaces was targeted to improve the composite conductivity and stability for electrochemical energy storage applications. Polyhedral cobalt oxide (Co3O4) was prepared using a molten salt combustion method and coated with polyaniline (PANI). The composite (PANI‐CoM) was characterized using XRD, TGA, FTIR, FESEM, TEM, and BET. From cyclic voltammetry analysis in 6 M KOH, PANI‐CoM shows a high CS (985 F/g) compared to bare Co3O4 (278 F/g), indicating that PANI coating has improved pseudocapacitive charge storability of the electrode. The electrolyte diffusion on the internal active surfaces has increased from 11% to 31%, contributed by the reduction of internal resistance by 29%. Activated carbon and ordered mesoporous carbon (OMC) were used to manufacture two sets of asymmetrical supercapacitor devices, and PANI‐CoM/OMC functioned the best performance with an ED of 22 Wh/kg at a PD of 400 W/kg.

Photocatalytic Degradation of Methyl Orange Dyes Using Green Synthesized MoS2/Co3O4 Nanohybrids

In this work, a new binary MoS2/Co3O4 nanohybrids was successfully fabricated and the chemical structures, morphologies, electrochemical and optical characterizations were carried out. In addition, heterojunction nanoparticles present in S-scheme structures act as electron traps and promote light absorption capacity for the degradation of Methyl orange (MO) with visible-light activity. MoS2/Co3O4 nanohybrids suggested excellent photocatalytic performance compared to bare MoS2 and Co3O4, where 95.6% of MO was degraded within 170 min, respectively. The results also showed excellent stability and recyclability over five consecutive cycles, without noticeable changes in the nanocomposite structure. The boosted photocatalytic degradation and redox activities of MoS2/Co3O4 can be attributed to the created S-scheme heterostructure to facilitate the separation of and to delay recombination of photoinduced charge carriers. We believe that this strategy of exploiting nanohybrid photocatalysts has great potential in the field of environmental catalysis and diverse applications.

Enhanced levofloxacin degradation by hierarchical porous Co3O4 with rich oxygen vacancies activating peroxymonosulfate: Performance and mechanism

Hierarchical porous Co3O4 with rich oxygen vacancies were fabricated by simple biotemplates derivatization method, and largely promoted the efficiency of peroxymonosulfate (PMS) activation to enhance levofloxacin (LVF) degradation by enlarging the specific surface area and introducing rich oxygen vacancy (Ovac). Results shows that hierarchical porous Co3O4 exposed more surface active sites, Co2+ and Ovac as active sites for PMS activation compared with that of bare Co3O4 obtained without biotemplates, giving rise to largely enhancement of catalytic performance, completely degrading 100% of LVF within 12 min by the optimum Co3O4-II. Besides, experimental studies confirmed that SO4− and electron transfer mechanism mainly contributed to LVF degradation in Co3O4-II/PMS system. The possible LVF degradation pathway was established on the base of the detected intermediates. This study not only improves the fundamental understanding of active sites in morphologically tunable metal oxides via biotemplates derivatization, but also provides guidance for the research and engineering application of peroxymonosulfate based advanced oxidation process in the future.

Nanoscale TiO2 Coatings Improve the Stability of an Earth-Abundant Cobalt Oxide Catalyst during Acidic Water Oxidation.

The large-scale deployment of proton-exchange membrane water electrolyzers for high-throughput sustainable hydrogen production requires transition from precious noble metal anode electrocatalysts to low-cost earth-abundant materials. However, such materials are commonly insufficiently stable and/or catalytically inactive at low pH, and positive potentials required to maintain high rates of the anodic oxygen evolution reaction (OER). To address this, we explore the effects of a dielectric nanoscale-thin layer, constituted of amorphous TiO2, on the stability and electrocatalytic activity of nanostructured OER anodes based on low-cost Co3O4. We demonstrate a direct correlation between the OER performance and the thickness of the atomic layer deposited TiO2 layers. An optimal TiO2 layer thickness of 4.4 nm enhances the anode lifetime by a factor of ca. 3, achieving 80 h of continuous electrolysis at pH near zero, while preserving high OER catalytic activity of the bare Co3O4 surface. Thinner and thicker TiO2 layers decrease the stability and activity, respectively. This is attributed to the pitting of the TiO2 layer at the optimal thickness, which allows for access to the catalytically active Co3O4 surface while stabilizing it against corrosion. These insights provide directions for the engineering of active and stable composite earth-abundant materials for acidic water splitting for high-throughput hydrogen production.

Significant enhancement of Z-Scheme mechanism based photocatalytic performance of Co3O4/ZnO–Cu nanocomposite for degradation of hazardous dye

Co3O4/ZnO–Cu nanocomposites (NCs) were successfully prepared by facile hydrothermal method. Photocatalytic activity of the prepared photocatalysts (PCs) were investigated under simulated light irradiation over Rhodamine Blue (Rh B) dye. The degradation efficiency of as-prepared Co3O4, ZnO–Cu, and Co3O4/ZnO–Cu PCs were 35.71, 64.47 and 95.33%, respectively. The significant PCs of Co3O4/ZnO–Cu NCs was achieved the better degradation efficiency (95.33%) within 100 min under simulated light irradiation. The kinetic rate constant of synthesized Co3O4/ZnO–Cu PCs (0.03086 min−1) was achieved by 6.76 times higher than bare Co3O4. The Co3O4/ZnO–Cu PCs showed an excellent recyclability with 90.7% of dye degradation efficiency after four successive cycles. Hence, the Co3O4/ZnO–Cu PCs have significant photocatalytic material due to great utilization of light fascination, effective charge separation and highly inhibits the recombination rate respectively. Since, the present finding suggests that the synthesized Co3O4/ZnO–Cu PCs can exhibit high potential towards wastewater treatment for various environmental applications.

Controllable synthesis of PtO modified mesoporous Co3O4 nanocrystals as a highly effective photocatalyst for degradation of Foron Blue dye

Incorporating noble metals on semiconductor photocatalysts can promote photoinduced hole–electron separation during the photocatalysis system, leading to improved photocatalytic efficiency. Herein, we report the incorporating of PtO nanoparticles (NPs) (0.3–1.2%) onto mesoporous p-type Co3O4 through a facile impregnation approach to remarkably enhance the photocatalytic ability for Foron Blue (FB) dye degradation under visible light illumination. The results indicated that complete FB dye degradation (100%) was obtained over 0.9% PtO/Co3O4 nanocomposite after 30 min illumination. The highest photocatalytic ability was acquired for 0.9% PtO/Co3O4 nanocomposite with the photodegradation rate of FB dye over approached 11.45 µmol L−1 min−1, which was four-fold larger than that of bare Co3O4 NPs. The highest k value (0.1070 min−1) for 0.9% PtO/Co3O4 photocatalyst was approximately 3.8 times higher than bare Co3O4 NPs (0.0298 min−1). The enhancement photocatalytic ability was referred to the construction heterojunction PtO/Co3O4 interfaces, which facilitated photoinduced charge carriers separation. The PtO/Co3O4 nanocomposites exhibited facile reusability and long-term stability, making them superior for practical application. To evidence our suggested mechanism and determine the mobility and separation efficiency of electron-hole, the photoluminescence (PL) and Transient photocurrent spectra were conducted.

Isotopic evidence for the tangled mechanism of the CO-PROX reaction over mixed and bare cobalt spinel catalysts

The catalytic performance of the bare Co3O4 and mixed cobalt-spinel catalysts (MxCo3−xO4; M = Cr, Mn, Fe, Ni, Cu, Zn) in the CO-PROX process was investigated in the temperature-programmed surface reaction (TPSR) mode using 18O2 as an oxidant.