Separation Of Photoinduced Charge Carriers Research Articles

One-step synthesis of P-doped poly(triazine imide) nanotubes with hybrid 1D/1D architecture and high-efficiency photocatalytic performance

Novel 3D P-doped poly(triazine imide) (PTI) nanotubes were prepared in situ by molten salt method with melamine and hexachlorotriphosphazene as starting precursors. The as-prepared composite showed superior photocatalytic properties under visible-light irradiation due to the integrated merits of 1D tubular structure, 1D nanorods, and P doping. The improved utilization of visible light and the enhanced separation of photo-induced charge carriers resulted in the maximum degradation rate constant of P-doped PTI at 2.86 min−1, which was approximately 6.3 and 2.6 folds those of bulk graphite-like carbon nitride and pristine PTI material, respectively, during tetracycline hydrochloride photodegradation. Moreover, the novel catalyst has an excellent stability and thus is a promising candidate for photocatalysis.

Room-temperature synthesized In-BiOBr1-xIx nanosheets with visible-light-driven superior photocatalytic activity: Degradation of dye/non-dye organic pollutants for environmental remediation

Photocatalysis is extensively investigated as a green, efficient and promising technique for environmental remediation. In this study, a series of template free In-doped BiOBrxI1-x photocatalysts have been successfully prepared at room temperature and characterized by various methods. Complete degradation of negatively charged methyl Orange, positively charged Rhodamine B and Methylene Blue organic dyes, and neutral and colorless non-dye organic compound of furfural was attained. The flat band potential offered the possibility of reduction of dissolved O2 to O2.− in the conduction band while the trapping experiment identified the (O2.−)is the main radical species followed by h+ for the photodegradation. In-BiOBrI-0.4 had an excellent photocatalytic degradation activity which could be due to the synergetic effect between metal ion doping and solid solution formation. It further promotes visible light-harvesting ability and photoinduced charge carrier separation efficiency. The order of the reaction rate was determined and the mechanism was proposed. This work can lay a base for the design of effective photocatalyst toward environmental remediation.

Fabricating structured 2D Ti3AlC2 MAX dispersed TiO2 heterostructure with Ni2P as a cocatalyst for efficient photocatalytic H2 production

Abstract A novel 2D MAX structure of Ti3AlC2 multilayers dispersed with TiO2/Ni2P heterojunction was designed and fabricated through modified sol-gel method for enhanced photocatalytic hydrogen production. Ni2P cocatalyst coupled 2D Ti3AlC2/TiO2 composite showed enhanced visible light absorption with promoted charge carrier separation. The activity of pristine Ti3AlC2 was obviously increased with the growth of TiO2 NPs and by exfoliating 2D MAX structure into multilayers. 2D Ti3AlC2/TiO2/Ni2P composite exhibited highest H2 production of 13000 μmol g−1 which was 1.29, 3.63 and 3.80 times more than the amount generated by TiO2/Ti3AlC2, TiO2/Ni2P and pristine TiO2, respectively. This enhanced activity was obviously due to good dispersion of TiO2/Ni2P over the Ti3AlC2 multilayers with boosted photoinduced charge carrier separation. Among the sacrificial reagents, glycerol-water mixture gave maximum H2 production due to the presence of more α-hydrogen atoms. More importantly, highest CO2 was evolved using a glycerol-water mixture compared to methanol, confirming both photocatalytic water splitting and photoreforming reactions occur simultaneously. The reaction mechanism to understand the role of each component in the composite catalyst is further discussed. The findings of this work would be helpful in commercial applications of Ti3AlC2 MAX based structured catalysts for H2 production and other sustainable energy systems.

Synthesis and Characterization of Efficient ZnO/g-C3N4 Nanocomposites Photocatalyst for Photocatalytic Degradation of Methylene Blue

We examine the photocatalytic activity (PCA) of ZnO/graphitic carbon nitride g-C3N4 (g-CN) composite material for methylene blue (MB) degradation under visible-light irradiation (VLI). The polymeric g-CN materials were fabricated by the pyrolysis of urea and thiourea. More importantly, ZnO/g-CN nanostructured composites were fabricated by adding the different mounts (60, 65, 70, and 75 wt.%) of g-CN into ZnO via the simple hydrothermal process. Among fabricated composites, the 75% ZnO/g-CN nanocomposites displayed a superior PCA for MB degradation, which were ~three-fold an enhancement over the pure ZnO nanoparticles. The fabricated materials have been evaluated by X-ray diffraction (XRD), UV-Vis, Fourier transform infrared (FT-IR) spectroscopy, and electron microscopy. More importantly, the photodegradation of MB could get 98% in ZnO/g-CN could be credited to efficient separation of photo-induced charge carriers between ZnO and g-CN. Also, the recycling efficiency of the as-prepared composites was studied for multiple cycles, which shows that the photocatalysts are stable and suitable to carry out photocatalytic degradation in the logistic mode. Additionally, the probable photocatalytic mechanism has also discussed. The synthetic procedure of ZnO/g-CN based materials can be used in numerous fields such as environmental and in energy storage applications.

In situ plasmonic Bi grown on I− doped Bi2WO6 for enhanced visible-light-driven photocatalysis to mineralize diverse refractory organic pollutants

Plasmonic Bi metal and I− dopant co-modified Bi2WO6 photocatalysts were successfully fabricated through a one-pot solvothermal method. The samples were characterized by multiple techniques to explore their crystalline structures, surface morphologies, photoelectric properties and photocatalytic performance. The photocatalytic activity of I-Bi/Bi2WO6 samples was evaluated by degrading diverse organic pollutants, including colorless Bisphenol A (BPA), cationic dye Rhodamine B (RhB), anionic dye Congo red (CoR), antibiotic Sulfamethoxazole (SX) and pesticide Atrazine (AZ). The results revealed that 1/5 I-Bi/Bi2WO6 (I:W = 1:5) possessed the best photocatalytic performance for degrading BPA, RhB, CoR, SX and AZ. The improved photocatalytic performance was mainly attributed to the enhanced the visible light harvesting caused by the impurity level generated via the I− dopant and effective separation and migration of photoinduced charge carriers. Moreover, the SPR effect of metallic Bi is also a key factor for the enhancement of photocatalytic performance. Additionally, the 1/5 I-Bi/Bi2WO6 sample also showed excellent photochemical stability after five cyclic tests. This work could be a basic platform for investigating impurity doping and surface metallization co-modified photocalysts with remarkable photocatalytic performance for the environmental pollution degradation.

CdS/ZnS/ZnO ternary heterostructure nanofibers fabricated by electrospinning for excellent photocatalytic hydrogen evolution without co-catalyst

AbstractIn recent years, ternary heterostructures (HSs) composed of three semiconductors have attracted significant attention because of the effective separation and transfer of photogenerated electrons and holes in these materials. In this work, new ternary CdS/ZnS/ZnO (CZZ) HSs with one-dimensional (1D) nanofiber morphology have been successfully fabricated for the first time by a series of processes: electrospinning ZnO nanofibers, sulfurizing ZnO in situ to form ZnS/ZnO binary HSs, and depositing CdS quantum dots in situ on the ZnS/ZnO HSs. Benefiting from the efficient separation and transfer of photoinduced charge carriers, the optimized CZZ ternary HSs exhibit a hydrogen evolution rate of 51.45 mmol h−1 g−1 (quantum efficiency: 26.88% at 420 nm) without any co-catalyst, which is 93.54 and 2.28 times higher than those exhibited by pristine ZnO and ZnS/ZnO binary HSs, respectively, under the same conditions. Furthermore, the rate of hydrogen evolution over the 1D CZZ nanofibers is significantly higher than that over 2D CZZ nanosheets (27.25 mmol h−1 g−1, in the presence of a Pt co-catalyst) prepared by the same sulfurization and deposition procedures. This can be ascribed to the significantly smaller geometric sizes of 1D nanofibers compared to those of 2D nanosheets, resulting in effectively suppressed recombination of photogenerated charge carriers and promotion of photocatalytic H2 evolution performance.

Photocatalytic decontamination of tetracycline and Cr(VI) by a novel α-FeOOH/FeS2 photocatalyst: One-pot hydrothermal synthesis and Z-scheme reaction mechanism insight

Tetracycline and Cr(VI) as non-biodegradable environmental contaminants have attracted increasing attention because of their chronic toxicity. In this regard, the environmentally friendly Z-scheme photocatalytic decontamination system has been widely used for contaminant treatment. Herein, a novel 3D Z-scheme α-FeOOH/FeS2 composite photocatalyst was successfully synthesized for the first time via a simple one-pot hydrothermal method. X-ray diffraction (XRD) and Fourier-transform infrared (FT-IR) analyses and high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) demonstrated that the O component of the heterogeneous nanostructures formed by the FeOFe linkages in α-FeOOH was replaced by S to generate FeSFe linkages in the resulting FeS2. As expected, the novel 3D Z-scheme α-FeOOH/FeS2 composites exhibited remarkable photocatalytic activity for Cr(VI) reduction and tetracycline degradation compared to pure α-FeOOH. Photoluminesence (PL) measurement and electrochemical impedance spectroscopy (EIS), as well as density functional theory (DFT) calculations, suggested that the enhanced photocatalytic activity of the Z-scheme α-FeOOH/FeS2 composite can be attributed to the improved photo-absorption properties and the effective separation of photo-induced charge carriers caused by the Z-scheme system of the as-prepared 3D α-FeOOH/FeS2 composites. Thus, this work may facilitate the effective design of α-FeOOH-based photocatalysts.

A facile route to construct NiTiO3/Bi4NbO8Cl heterostructures for enhanced photocatalytic water purification

NiTiO3/Bi4NbO8Cl heterostructure photocatalysts were successfully synthesized by a mechanical mixing method. The crystal structure, morphology, optical properties and energy band structures of all samples were determined by X-ray powder diffraction, X-ray photoelectron spectroscopy, scanning electron microscope, transmission electron microscope, ultraviolet–visible diffuse reflection spectra (UV–Vis DRS), and Mott–Schottky tests. The NiTiO3/Bi4NbO8Cl composites were observed to possess an improved activity in the photocatalytic degradation of organic dye rhodamine B (RhB) under irradiation. In particular, Bi4NbO8Cl modified with NiTiO3 (10% in weight) exhibits the best photocatalytic performance. The enhanced photocatalytic performance can be ascribed to the formation of intimate interfacial contact and type-II band alignment between NiTiO3 and Bi4NbO8Cl. From the results of photoluminescence spectra (PL), time-resolved decay spectra (TR-PL), photocurrent and electrochemical impedance spectroscopy, the rapid separation and transportation of photoinduced charge carriers were proved. In addition, the proposed mechanism for the enhanced photocatalytic activities is proposed in this paper.

Preparation of magnetically recoverable and Z-scheme BaFe12O19/AgBr composite for degradation of 2-Mercaptobenzothiazole and Methyl orange under visible light

Here, a series of BaFe12O19/AgBr magnetic recyclable composites were designed for the removal of 2‑Mercaptobenzothiazole (MBT) and Methyl orange (MO) under visible light. The vibrating sample magnetometer test demonstrated that composites exhibit superior magnetic recyclability. Among all composites, 10% BaFe12O19/AgBr exhibited the highest reaction rate (0.1005 min−1) of MBT degradation, which was about 3.32 and 71.79 times higher than that of pure AgBr (0.0302 min−1) and BaFe12O19 (0.0014 min−1), respectively. Besides, the composites also exhibited obviously improved photocatalytic MO degradation properties. The excellent photocatalytic activity could be ascribed to the efficient separation of photo-induced charge carriers, which was certificated by cyclic voltammogram (CV), transient photocurrent tests, electrochemical impedance spectroscopy (EIS) and photoluminescence (PL) spectra. Capture experiments proved that O2−, h+ and OH are the main active species in the process of MBT degradation, which matches well with the results of electron spin resonance (ESR) measurements. Moreover, the test of Mott-Schottky plots verified the flat band potentials of catalysts. At last, a possible Z-scheme reaction mechanism for the photocatalytic system was proposed. This work will provide theoretical guidance for the construction of magnetically recyclable Z-type photocatalysts.

Photocatalytic activation of peroxymonosulfate by surface-tailored carbon quantum dots

In this study, carbon quantum dots (CQDs) were synthesized by a low-cost and scalable approach and the oxygen functional groups were fine-tuned by chemical post-treatment. It was found that the CQDs could be applied as visible-light-responsive photocatalysts for activation of peroxymonosulfate (PMS) and remediation of aqueous organic dyes. Phenylhydrazine modified CQDs (CQDs-PH) presented high efficiency for degradation of methylene blue due to selective removal of carboxylic groups and inhibited recombination of photogenerated electron-hole pairs. The effects of catalyst dosage, species and concentrations of dyes, and initial pH values on the photodegradation efficiency were systematically investigated and the alkaline condition facilitates the separation of photoinduced charge carriers and promotes the dye decoloration. The reactive oxygen species produced in the photocatalysis were identified by radical quenching tests and the mechanism was elucidated. Superoxide radicals were generated from PMS activation via electron transfer from CQDs and played the primary role in organic oxidation. In addition, photogenerated holes on the valence band of CQDs also participated in the dye decomposition.

Facile Fabrication of Z-Scheme Bi2WO6/WO3 Composites for Efficient Photodegradation of Bisphenol A with Peroxymonosulfate Activation.

The rational fabrication of direct Z-scheme heterostructures photocatalysts is a pivotal strategy to boost the interfacial charge migration and separation. Herein, direct Z-scheme Bi2WO6/WO3 composites were rationally fabricated for the degradation of bisphenol A combined with the activation of peroxymonosulfate (PMS). The tight interface contact between Bi2WO6 and WO3 was successfully formed by the in situ epitaxial growth of ultrathin Bi2WO6 nanosheets at the surface of WO3 nanorods. The Bi2WO6/WO3 composite presented highly efficient catalytic performance toward degradation of BPA with PMS activation as compared to the WO3 and Bi2WO6. PMS can dramatically boost the photocatalytic activity of the composites. Moreover, the results of active radical scavenging experiments revealed that h+, •O2−, and •SO4− are critical active species in the photodegradation reaction. Finally, the photocatalytic mechanism for the degradation of BPA is also discussed in detail. The great improvement of photocatalytic performance should be ascribed to the effective formation of the direct Z-scheme heterojunctions between Bi2WO6 and WO3, resulting in improved light absorption, an efficient transfer and separation of photoinduced charge carriers, and a considerable amount of the electrons and holes with strong reduction and oxidation abilities. The study might provide new inspirations to design and construct heterostructured nanomaterials with outstanding photoactivity for environmental remediation.

2D/2D Mt/m-CN composite with enriched interface charge transfer for boosting photocatalytic CO2 hydrogenation by H2 to CH4 under visible light

Well-designed montmorillonite (Mt) coupled graphitic carbon nitride (m-CN) composite for stimulating photocatalytic CO2 hydrogenation with H2 and H2O reducing agents has been investigated. 2D Mt nanosheets were uniformly anchored with 2D m-CN nanosheets for improving charge carrier separation. The photoactivity of 2D/2D Mt/m-CN was tested for CO2 photoreduction with H2O/H2 to CO/CH4 through RWGS and CO2 methanation reactions under visible light. Using 20% Mt/m-CN, highest CO and CH4 yield rate of 253 and 165 μmol g-cat−1h−1 were obtained, 5.9 and 6.4 times high than g-C3N4, respectively. This improved activity reflects synergistic effect between Mt and m-CN, which promotes photo-induced charge carrier separation. More interestingly, during CO2 reduction with hydrogen, CH4 was the main product and its production was 2.1 folds higher than using CO2 reduction by H2O. This selective CO2 hydrogenation to methane was obviously due to single-step CO2 methanation process with proficient H2 oxidation over highly efficient Mt/m-CN composite. The QY for CH4 production of 4.55% was obtained with high stability in cycles over the composite catalyst. The findings from this research would be fruitful for further investigation in CO2 conversion for selective fuels production to provide clean energy.

Facile Synthesis of a Z-Scheme ZnIn2S4/MoO3 Heterojunction with Enhanced Photocatalytic Activity under Visible Light Irradiation.

Employing a visible-light-driven direct Z-scheme photocatalytic system for the abatement of organic pollutants has become the key scientific approach in the area of photocatalysis. In this study, a highly efficient Z-scheme ZnIn2S4/MoO3 heterojunction was prepared through the hydrothermal method, followed by the impregnation technique that facilitates the formation of an interface between the two phases for efficient photocatalysis. The structural, optical, and surface elemental composition and morphology of the prepared samples were characterized in detail through X-ray diffraction, UV–vis diffuse reflectance spectra, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The results indicate that the composite materials have a strong intimate contact between the two phases, which is beneficial for the effective separation of photoinduced charge carriers. The visible-light-mediated photocatalytic activity of the samples was tested by studying the degradation of methyl orange (MO), rhodamine B (RhB), and paracetamol in aqueous suspension. An optimum loading content of 40 wt % ZnIn2S4/MoO3 exhibits the best degradation efficiency toward the above pollutants compared to bare MoO3 and ZnIn2S4. The improved photocatalytic activity could be ascribed to the efficient light-harvesting property and prolonged charge separation ability of the Z-scheme ZnIn2S4/MoO3 catalyst. Based on reactive species determination results, the Z-scheme charge transfer mechanism of ZnIn2S4/MoO3 was discussed and proposed. This study paves the way toward the development of highly efficient direct Z-scheme structures for a multitude of applications.

Fabrication of Ce3+ substituted nickel ferrite-reduced graphene oxide heterojunction with high photocatalytic activity under visible light irradiation

In the current investigation, graphene (rGO)-supported cerium substituted nickel ferrite (NiCeyFe2-yO4 y = 0.05) photocatalyst was prepared via two-step wet chemical approach. The resulting NiCeyFe2-yO4/rGO nanocomposite exhibited excellent photocatalytic performance and stability. Moreover, the photocatalytic activity of NiCeyFe2-yO4/rGO nanocomposite was also investigated comparatively with NiCeyFe2-yO4 nanoparticles. As compared to the NiCeyFe2-yO4 nanoparticles, NiCeyFe2-yO4/rGO nanocomposite showed superior photocatalytic efficiency and recycling stability for MB degradation, which is two times that of bare NiCeyFe2-yO4 nanoparticles. After visible light irradiation for 70 min, 94.67 % of MB dye was removed by NiCeyFe2-yO4/rGO nanocomposite whereas only 50 % of MB dye was removed by NiCeyFe2-yO4 nanoparticles. The increase in photocatalytic performance is mainly ascribed to formation of NiCeyFe2-yO4/rGO heterojunction which not only assist in separation of photo-induced charge carriers, but also sustain a strong redox ability. Moreover, the photo-corrosion of NiCe0.05Fe1.95O4 nanoparticles is inhibited through transfer of photo-induced electrons of NiCe0.05Fe1.95O4 nanoparticles to rGO. A possible photo-degradation mechanism based on reactive species trapping experiments has been proposed. The effect of various factors like pH, temperature and catalyst dosage has also been explored. Facile synthesis method, excellent photocatalytic performance for organic pollutants and superior reusability suggest that NiCeyFe2-yO4/rGO photocatalyst possesses high potential for large-scale pollutant treatment.

Mesoporous TiO2/g-C3N4 composites with O-Ti-N bridge for improved visible-light photodegradation of enrofloxacin

g-C3N4 makes good prospects in photocatalytic field due to its two-dimensional (2D) structure and visible-light activity. How to improve its photocatalytic activity by minimizing the unexpected recombination of photo-induced charge carries on g-C3N4 motivates our research. Herein, mesoporous TiO2/g-C3N4 composites are fabricated with 2D TiO2(B) nanosheets regulating thermal condensation process of g-C3N4 nanosheets. FT-IR and XPS results suggest that the formation of O-Ti-N chemical bond increases the percentage of N-(C)3 in the conjugated system, accelerating the transportation of photo-induced electrons. The optical property and PL results illustrate that the formed interface heterojunction with chemical bond facilitates the separation and transfer of photo-induced charge carriers. Hence, the removal constant of TiO2/g-C3N4 composites is 46.3 times higher than that of g-C3N4. This study opens up a new insight into the development of composite materials in the field of organic pollutant treatment.

Sulfur Doped Carbon-Rich g-C3N4 for Enhanced Photocatalytic H2 Evolution: Morphology and Crystallinity Effect

Molecular design for the intercalation of S and C in the framework of g-C3N4 is a promising strategy to increase visible light harvesting and facilitate the separation of photoinduced electron/hole pairs. Herein, we reported a facial method to prepare porous S doped g-C3N4 nanotubes by thermal polymerization of urea and 2-thiobarbituric acid. The obtained catalysts contain certain carbon and sulfur atoms in the aromatic rings substituting the nitrogen atoms in g-C3N4, which narrows down the band gap, and increases the separation of photoinduced charge carriers. Meanwhile, nanotube formation increases the specific surface area of catalyst. The synergistic effect of S doped carbon rich g-C3N4 and nanostructure forming results in superior photocatalytic H2 evolution from water splitting. The study shows that the photocatalytic H2 evolution is correlated with the crystallinity of S doped g-C3N4. Schematic illustration for framework of 0.3S-CN and its photocatalytic hydrogen evolution mechanism.

Hydrogen production from natural organic matter via cascading oxic-anoxic photocatalytic processes: An energy recovering water purification technology

Photocatalysis provides a “green” strategy to produce the clean energy of H2. However, the realization of efficient H2 production is usually accomplished by the consumption of electron donors, which are costly energy carriers themselves. Here, we attempted to utilize the naturally abundant humic acid (HA), a representative natural organic matter (NOM), as the source of electron donor in a cascading oxic-anoxic photocatalytic system. Results showed that degradation of HA and remarkable H2 yield (1660.9 μmol g−1 h−1 at optimal condition) were obtained successively, whereas the anoxic photocatalytic treatment of pristine HA did not improve H2 yield but substantially eliminated the H2 production and HA degradation efficiency. These phenomena suggested the preoxidation process played a vital role in counteracting the detrimental effect of HA on photocatalytic H2 production. Electrochemical measurement indicated that the preoxidized HA harbored more redox-active moieties than the untreated HA and thus leading to a higher photo-induced charge carrier separation efficiency. A variety of advanced spectroscopic analyses revealed that the photocatalytic oxic pre-treatment resulted in breakdown of chemically inert, electron mediating and chromophoric aromatic macrostructure of HA to form smaller sized oxygenated organic intermediates. These intermediates were more nucleophilic than the pristine HA and acted as sacrificial reagent in the subsequent anoxic process for boosting H2 production. This study showcases an energy recovering water remediation process and paves the way for the design of novel photocatalytic technologies for environmental application.

Highly Stable Phosphonate-Based MOFs with Engineered Bandgaps for Efficient Photocatalytic Hydrogen Production.

Photoactive metal-organic frameworks (MOFs) represent one of the most promising materials for photocatalytic hydrogen production, but phosphonate-based MOFs have remained largely underdeveloped compared to other conventional MOFs. Herein, a photocatalyst of 1D titanium phosphonate MOF is designed through an easy and scalable stirring hydrothermal method. Homogeneous incorporation of organophosphonic linkers can narrow the bandgap, which is due to the strong electron-donating ability of the OH functional group that can efficiently shift the top of the valence band, moving the light absorption to the visible portion of the spectrum. In addition, the unique 1D nanowire topology enhances the photoinduced charge carrier transport and separation. Accordingly, the titanium phosphonate nanowires deliver remarkably enhanced photocatalytic hydrogen evolution activity under irradiation of both visible light and a full-spectrum simulator. Such concepts of engineering both nanostructures and electronic states herald a new paradigm for designing MOF-based photocatalysts.

Synergetic effect of C60/g‐C3N4 nanowire composites for enhanced photocatalytic H2 evolution under visible light irradiation

AbstractC60 functioned g‐C3N4 nanocomposites were prepared by calcining the mixture of urea and C60 nanorods formed via a liquid‐liquid interfacial precipitation method. The obtained C60/g‐C3N4 nanowire composites exhibit better utilization of solar energy, efficient transfer and separation of photoinduced charge carriers. The optimum photocatalytic H2 evolution rate for C60/g‐C3N4‐0.03 wt % containing 0.03 wt % C60 under visible light irradiation reaches 8.73 μmol/h (with quantum efficiency of 5.10 %), which is about 4.7 times as high as that of pure g‐C3N4. This remarkable enhanced photocatalytic performance of C60/g‐C3N4‐0.03 wt % is mainly attributed to the synergistic effect of the interface formed between g‐C3N4 and C60 nanorods.

Turning the activity of Cr–Ce mixed oxide towards thermocatalytic NO oxidation and photocatalytic CO2 reduction via the formation of yolk shell structure hollow microspheres

Cr–Ce mixed oxides microspheres will have considerable potential in thermocatalytic NO oxidation and photocatalytic CO2 reduction reaction (CO2RR) if their low porosity and expensive synthetic expenditure can be overcome. To avoid these obstacles, a facile and economical strategy was adopted to synthesize double-shelled hollow Cr–Ce mixed oxide microspheres. The highly active multipurpose catalyst achieved an ultrahigh thermocatalytic NO oxidation efficiency at low temperatures, and provided high yields of CH4 and CH3OH during the photocatalytic CO2RR. For NO oxidation, the optimized catalyst provided over 40% NO removal at 150 °C, which was ascribed to the reduced aggregation of the active subunits and the increased active species availability. Further, the exposed surface could generate an increased content of Cr6+ and Oβ, which played the key role in NO oxidation. For CO2 photocatalytic reduction, the superior behavior originated from the reduced band gap and the effective separation of photoinduced charge carriers. This study opens up new possibilities of using Cr–Ce mixed oxides for application in catalysis.