Construction of Au/TiO2 Heterojunction with high photocatalytic performances under UVA illumination

Anatase TiO₂ nanoparticles (NPs) were successfully prepared through a hydrothermal approach, and Au NPs at various Au (0.1–2 wt%) contents were photodeposited onto the TiO₂ NPs surface. The photocatalytic efficiency for the Au/TiO₂ NPs for resorcinol photodegradation throughout UVA illumination was assessed. The TEM images and XPS findings indicated that the Au NPs are highly distributed onto TiO₂ surface in the metallic state. The 0.1%Au/TiO₂ NPs exhibited the highest photocatalytic efficiency of about 95.34%; however, 72.36% is given by pure TiO₂ NPs. It was found that the photodegradation rate of 0.1% Au/TiO₂ NPs exhibited 1.5 times of magnitude higher than pure TiO₂ NPs. 0.1%Au/TiO₂ NPs was considered to be the outstanding photoactive due to the ultimate efficient charge-carriers separation through charge transfer between Au and TiO₂ NPs. The Au NPs sizes, its dispersity on TiO₂ surface and surface plasmon resonance (SPR) were believed the critical factors for the higher photocatalytic performance of 0.1% Au/TiO₂ NPs. The prepared photocatalysts are found to be the promising materials for toxic organic compounds remediation and solar conversion.     

A unique Cu2O/TiO2 nanocomposite with enhanced photocatalytic performance under visible light irradiation

A unique Cu₂O/TiO₂ nanocomposite with high photocatalytic activity was synthesized via a two-step chemical solution method and used for the photocatalytic degradation of organic dye. The structure, morphology, composition, optical and photocatalytic properties of the as-prepared samples were investigated in detail. The results suggested that the Cu₂O/TiO₂ nanocomposite is composed of hierarchical TiO₂ hollow microstructure coated by a great many Cu₂O nanoparticles. The photocatalytic performance of Cu₂O/TiO₂ nanocomposite was evaluated by the photodegradation of methylene blue (MB) under visible light, and compared with those of the pure TiO₂ and Cu₂O photocatalysts synthesized by the identical synthetic route. Within 120 min of reaction time, nearly 100% decolorization efficiency of MB was achieved by Cu₂O/TiO₂ photocatalyst, which is much higher than that of pure TiO₂ (26%) or Cu₂O (32%). The outstanding photocatalytic efficiency was mainly ascribed to the unique architecture, the extended photoresponse range and efficient separation of the electron-hole pairs in the Cu₂O/TiO₂ heterojunction. In addition, the Cu₂O/TiO₂ nanocomposite also retains good cycling stability in the photodegradation of MB.     

Construction of CoS/CeO2 heterostructure nanocages with enhanced photocatalytic performance under visible light

Exploring non-noble metal photocatalysts with high activity and stability is always fascinating. Herein, the hollow CoS nanocages deriven from ZIF-67 have been reported for the first time to combine with CeO₂ NPs grown in situ for photocatalytic degradation of stubborn pollutants. The unique CoS nanocages not only provide rich active sites but also enhance light capture. CeO₂ NPs loaded on the surface accelerate the separation of photocharges and extend the lifetime of photogenerated carriers. The optimized photocatalysts show outstanding activity and stability for the photodegradation of tetracycline and phenol under visible light, and the corresponding photodegradation efficiency is 96.5% and 90.5% at 60 minutes. The novel multi-stage nanocage structure simultaneously realizes extended light absorption and improved photocharges transfer efficiency. This work provides an exclusive perspective to design high-efficiency photocatalysts with hollow structures for environmental restoration.     

In-situ generation Cu2O/CuO core-shell heterostructure based on copper oxide nanowires with enhanced visible-light photocatalytic antibacterial activity

As visible light-driven photocatalysts in wastewater treatment, Cu₂O/CuO composites have garnered considerable attention. Herein, Cu₂O/CuO core–shell nanowires were fabricated directly on a Cu mesh using a simple two-step synthesis process involving a wet chemical method and rapid annealing. Unlike conventional composite nanowires, controllable core–shell nanowires exhibit high photoelectrochemical properties and overcome the problems associated with the recovery of powder-based photocatalysts. The presence and structural distribution of the Cu₂O/CuO core–shell nanowires were confirmed using X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy. Among the samples subjected to different rapid annealing temperatures for 180 s, the sample exposed to rapid annealing at 350 °C achieved the highest photocurrent density of ?6.96 mA cm^?2. In the core–shell nanowires fabricated on the samples, the ratio of Cu₂O/CuO was 1:1. The photocatalytic activity of the Cu₂O/CuO nanowire samples was also determined by measuring methyl blue degradation to determine their applicability in wastewater treatment. A remarkable photocatalytic degradation rate of 91.6% was achieved at a loading bias voltage of ?0.5 V. The Cu₂O/CuO heterojunction enhanced the photodegradation of the samples because the different bandgaps improved the dissociation of the photogenerated electron–hole pairs. Furthermore, the antibacterial activity of the Cu₂O/CuO nanowires exhibited considerable resistance against Escherichia coli and photocatalytic antibacterial treatment for only 20 min under visible light killed 10⁶ CFU/mL of E. coli. Therefore, the Cu₂O/CuO controllable core–shell nanowires with a high photodegradation performance and excellent antibacterial activity under general illumination show diverse applications in water treatment.     

Aerosol processing of Ag/TiO2 composite nanoparticles for enhanced photocatalytic water treatment under UV and visible light irradiation

In this study, we investigated the effect of Ag addition on the photocatalytic reactivity of TiO₂ nanoparticles (NPs). Controlled amounts of Ag were incorporated in TiO₂ NPs using aerosol spray pyrolysis and subsequent calcination. Ag/TiO₂ composite NPs containing different amounts of Ag (e.g., 0, 0.5, 1, 2, and 5 wt%) were successfully fabricated. The photodegradation performances of the as-prepared Ag/TiO₂ composite NPs were tested using methylene blue (MB) solution under UV and visible light irradiation. Upon increasing the Ag content to 1 wt%, the resulting Ag/TiO₂ composite NPs exhibited increased photocatalytic reactivity due to lowered bandgap energy, which promoted both charge generation and separation. However, when the Ag content exceeded 1 wt%, the photocatalytic reactivity of the resulting Ag/TiO₂ composite NPs was considerably deteriorated due to the masking effect of the excess Ag on the reactive sites of TiO₂. Hence, the incorporation of an optimized amount of Ag in the TiO₂ matrix promotes the photocatalytic reactivity of Ag/TiO₂ composite NPs by controlling their bandgap energy and charge generation and separation processes. These results could lead to the development of photodegradation active substances for water treatment in organic solutions.     

Au nanoparticles-doped g-C3N4 nanocomposites for enhanced photocatalytic performance under visible light illumination

Surface and bandgap engineering of graphitic carbon nitride (g-C₃N₄) could be vital in enhancing photocatalytic performance by suppressing the recombination rate of photogenerated electron-hole pairs. The present report investigated the doping effects of various wt.% (0.2–5.0%) of gold nanoparticles (Au NPs) to g-C₃N₄ (Au/g-C₃N₄) for the enhancement of the photocatalytic efficiency of g-C₃N₄ nanocomposites. A straightforward and cost-effective synthesis methodology has been applied for the desired nanocomposites. Relevant characterization tools such as XRD, XPS, TEM, FTIR, and UV–Vis were utilized to analyze various physicochemical properties. The TEM images clearly show that spherical Au NPs were homogeneously distributed into the thin carbon nitride graphitic layers, confirming the successful doping of Au. The higher-magnification TEM image confirms that the sizes of the Au NPs varied from 15 to 25 nm. The photoactivity of the newly designed Au/g-C₃N₄ nanocomposites has been evaluated for the degradation of both methylene blue dye and the drug gemifloxacin mesylate, and their efficiencies were compared with that of bare g-C₃N₄. Our findings revealed that Au/g-C₃N₄ nanocomposites with various Au contents had superior photocatalytic activity compared to bare g-C₃N₄. However, the 1%Au/g-C₃N₄ nanocomposite could be considered the optimum photocatalyst, producing 95.13% destruction of the target dye molecule in 90 min, in contrast to the 69% achieved with bare g-C3N4, under the clean energy of visible light illumination. Additionally, the photodegradation rate of the 1%Au/g-C₃N₄ nanocomposite is 2.69 times higher than the rate of bare g-C₃N₄. This report might open a new gateway towards a straightforward and cost-effective synthesis approach for Au/g-C₃N₄ nanocomposites and provides a smooth and robust platform for the utilization of this new nanocomposite for environmental remediation processes.     

Photocatalytic hydrogen production by Au–MxOy (MAg,Cu, Ni) catalysts supported on TiO2

Au–M_xO_y (MAg, Cu, Ni) nanoparticles supported on TiO₂–P25 were prepared by the deposition–precipitation method and were evaluated for the photocatalytic water splitting reaction for hydrogen production, using a mixture of water–methanol (1:1). The combinations of Au–Cu₂O/TiO₂ and Au–NiO/TiO₂ effectively increased the hydrogen production (2064 and 1636 μmol·h^− 1·g^− 1) obtained by Au/TiO₂ (1204 μmol·h^− 1·g^− 1). The higher photoactivities achieved by Au–Cu₂O and Au–NiO nanoparticles deposited on TiO₂ were attributed to an enhancement of the electron charge transfer from TiO₂ to the Au–M_xO_y systems and the effect of surface plasmon resonance of gold nanoparticles.     

Dye-sensitized solar cell performance and photocatalytic activity enhancement using binary zinc oxide-copper oxide nanocomposites prepared via co-precipitation route

Zinc oxide nanoparticles (ZnO NPs) and binary ZnO–CuO nanocomposites (ZnO–CuO NCs) were prepared through a simple chemical co-precipitation route. The influence of copper (Cu²⁺) ions concentration (0.03, 0.06, 0.09, and 0.12 M) on optical, morphological, structural, and elemental characteristics of the ZnO–CuO NCs was examined by appropriate characterization techniques. The visible light reactive CuO created absorption shift to red region that minimized band gap of the ZnO–CuO NCs. The concentration of Cu²⁺ ions produced appreciable impact on size of the ZnO–CuO NCs. The dye-sensitized solar cell (DSSC) constructed using ZnO–CuO NC photoanode with Cu²⁺ ions concentration of 0.06 M generated a conclusive solar to electrical energy transformation efficiency of 2.56%, which was a 2.2-times greater over the DSSC encompassed pristine photoanode of ZnO NPs. The electrochemical impedance spectroscopy analysis revealed the longer lifetime of the photogenerated electrons and reduction in the charge recombination rate in the ZnO_(0.44)–Cu_(0.06) NC photoanode based DSSC. Furthermore, the ZnO_(0.44)–Cu_(0.06) NC disclosed substantial photocatalytic activity towards methylene blue dye degradation that could be chiefly credited to its particles size induced visible light absorption property.     

High-performance Cu2O-based photocatalysts enabled by self-curling nanocelluloses via a freeze-drying route

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.     

The Z-scheme heterojunction between TiO2 nanotubes and Cu2O nanoparticles mediated by Ag nanoparticles for enhanced photocatalytic stability and activity under visible light

The photocatalytic reduction method was used to introduce Ag nanoparticles (Ag NPs) into the Cu₂O-TiO₂ nanotubes (Cu₂O-TNT) prepared by electrodeposition. The Z-scheme heterojunction Cu₂O-Ag-TNT (CAT-4–60) catalysts were prepared. The mechanism of the transition from the traditional P-N heterojunction enhanced by noble metal to the Z-scheme heterojunction was studied. In addition, the Z-scheme heterojunction CAT-4–60 showed the highest light absorption and the highest photoelectrochemical activity under visible light, and the photoluminescence intensity was significantly reduced. Compared with the traditional P-N heterojunction CAT-2–60, not only the photocatalytic activity of the dual Z-scheme CAT-4–60 catalyst was improved, and the removal rate of MB was 98.58% higher than TNT (45.81%), CT-60 (69.49%), AT-2 (75.1%) and CAT-2–60 (91.2%),but also the stability of Cu₂O in CAT-4–60 was significantly enhanced. This work reveals the potential application of noble metal nanoparticles to enhance the Z-scheme heterojunction under visible light-driven photocatalysis, and provides new insights to the transition from traditional P-N heterojunctions to Z-scheme heterojunctions.     

Ir promotion of TiO2 supported Au catalysts for selective hydrogenation of cinnamaldehyde

We synthesized Ir-on-Au (Au–Ir) nanoparticles (NPs) using 8–9 nm Au NPs, which had a partial coverage of Ir. Both the studied systems allowed the obtainment of cinnamyl alcohol with high selectivities (> 83%). However, Au–Ir/TiO₂ delivered a hydrogenation rate 5 times higher than that of Au/TiO₂. The deposition of Ir onto the surface of Au and the presence of surface Au–Ir alloy were confirmed by UV–vis and HRTEM respectively. Moreover. Moreover, the strongly shifted XPS binding energy implyed the electron transfer from Ir to Au, which was believed to be responsible for the enhanced H₂ activation capacity of Au.     

Cu2O/TiO2 heterostructure nanotube arrays prepared by an electrodeposition method exhibiting enhanced photocatalytic activity for CO2 reduction to methanol

Cu₂O/TiO₂ composite nanotube arrays demonstrating enhanced photocatalytic performance were synthesized using an electrodeposition method to impregnate the p-type Cu₂O into the n-type titanium dioxide nanotube arrays (TNTs). The morphological results confirmed that the TNTs are wrapped by the Cu₂O nanoparticles and the UV–Vis absorption spectra showed that the Cu₂O/TNTs display a better ability for visible light absorption compared to the pure TNTs. CO₂ photocatalytic reduction experiments carried out by using Cu₂O/TNT nanocomposites proved that Cu₂O/TNTs exhibit high photocatalytic activity in conversion of CO₂ to methanol, while pure TNT arrays were almost inactive. Furthermore, Cu₂O/TNTs also exhibited augmented activity in degradation of target organic pollutant like acid orange (AO) under visible light irradiation. The ultra enhanced photocatalytic activity noticed by using Cu₂O/TNTs in CO₂ reduction and degradation of organic pollutant could be attributed to the formation of Cu₂O/TiO₂ heterostructures with higher charge separation efficiency.     

Synthesis and enhanced bias-free photoelectrochemical water-splitting activity of ferroelectric BaTiO3/Cu2O heterostructures under solar light irradiation

Here, we first use a facile electrochemical deposition method to load Cu₂O nanoparticles onto the BaTiO₃ (BTO) surface to prepare BTO/Cu₂O heterostructure photoanodes. Compared to the pure BTO photoanode, all BTO/Cu₂O heterostructure photoanodes show outstanding visible light harvesting ability and greatly improved photoelectrochemical water splitting performance. By optimizing the loading amount of Cu₂O nanoparticles, the photocurrent density achieved by BTO/Cu₂O-100 photoanode is 0.26 mA/cm² at 0 V versus Ag/AgCl, which is 2.6 times that of the bare BTO photoanode. In contrast with the photocurrent densities of the other reported BTO-based heterostructure photoanodes, the photocurrent density achieved by the present BTO/Cu₂O-100 photoanode without bias voltage is much higher. Additionally, the maximum solar-to-hydrogen conversion efficiency of the BTO/Cu₂O-100 heterostructure photoanode is 0.11% at 0.72 V versus reversible hydrogen electrode, approximately double that of BTO photoanode. The measurements of diffuse reflectance spectra, photoelectrochemical impedance and the room temperature photoluminescence spectra demonstrate that the improved photoelectrochemical performance contributes from the visible light absorption ability of Cu₂O nanoparticles, efficient transport and separation of photogenerated electron-hole pairs, which are induced by the spontaneous polarization electric field of ferroelectric BTO, p-n junction and type-II band alignment of BTO/Cu₂O heterostructure photoanode. A possible mechanism for the improved photoelectrochemical water splitting performance and charge transfer process is proposed.     

Ternary Pt@TiO2/rGO Nanocomposite to Boost Photocatalytic Activity for Environmental and Energy Use

This work explores the effect of ternary nanostructure for the enhanced photocatalytic degradation of pollutants and dyes. One-pot solvothermal-assisted approach was used for producing nanosized Pt@TiO₂ hybrid nanoparticles (NPs) decorated on reduced graphene oxide (rGO) layers. The microstructure, morphology, chemical composition, and optical absorption of the designed photocatalyst was successfully characterized (using XRD, TEM, Raman, UV–visible absorption spectra, and XPS techniques). The ternary Pt@TiO₂-rGO photocatalyst consist of monodisperse quasi-spherical Pt@TiO₂ NPs with an average size of 11 nm deposited on the rGO nanosheets. Furthermore, Pt@TiO₂-rGO was further investigated for the photodegradation of pesticide and dyes under UV and visible light. The ternary Pt@TiO₂-rGO photocatalyst proved a significant improvement on the photodecomposition of pollutants compared to hybrid Pt@TiO₂. The Pt@TiO₂-rGO photocatalyst was found to show seven- and threefold increase in the photocatalytic activity compared to TiO₂ and Pt@TiO₂ NPs, respectively which resulted from the high surface area of rGO and as well as the strong Pt/TiO₂/rGO interactions which ensured excellent properties of charge separation. On the other hand, the ternary photocatalyst exhibited very good recycle and reuse capacity up to five cycles.

     

A novel method for the synthesis of Fe3O4 nanoparticles/CdS nanowires heterostructure nanocomposite and uses in photodegradation of methylene blue

We report here a simple, efficient, practical, and novel method for the preparation of Fe₃O₄ nanoparticles (NPs)/CdS nanowires. The CdS nanowire/Fe₃O₄ NP reported here was characterized by transmission electron microscopy (TEM), X-ray Diffraction (XRD), vibrating sample magnetometer (VSM), and energy-dispersive X-ray. Cadmium diethyl dithiophosphate has been used as a 3 in 1 precursor (cadmium, sulfur, and ligand source) for the synthesis of high-quality one-dimensional Fe₃O₄ NPs/CdS nanowires using a simple hydrothermal method in the presence of Fe₃O₄ NPs in water. Photocatalytic activity studies show that the nanocomposite has good photocatalytic activity toward the photodegradation of methylene blue in an aqueous solution.     

Preparation and characterization of Ag3PO4/BiOI composites with enhanced visible light driven photocatalytic performance

Ag₃PO₄/BiOI composites were successfully prepared by a facial room temperature liquid phase method. Ag₃PO₄ nanoparticles were uniformly distributed on the surface of BiOI nanosheets. The photodegradation tests show that the photocatalytic efficiency was increased at first and then decreased when further increasing Ag₃PO₄ content in the composites. The best photocatalytic performance was obtained for the sample with Ag/Bi ratio of 0.3 and the photodegradation efficiency of Ag₃PO₄/BiOI was nearly 10 times that of BiOI. The enhanced photocatalytic activity of the composites was due to the improved photogenerated carrier separation capacity, being induced by the coupling effects of the two semiconductors.     

Fabrication of plasmonic Au/TiO2 nanotube arrays with enhanced photoelectrocatalytic activities

Uniformly dispersed Au nanoparticles (NPs) deposited on the surface of highly ordered TiO₂ nanotube arrays (Au/TiO₂ NTs) were synthesized through a two-step process including anodization method and microwave-assisted chemical reduction route. The investigation indicated that Au NPs grew uniformly on the walls of TiO₂ NTs. Au/TiO₂ NTs exhibited excellent visible light absorption due to the LSPR effect of Au NPs. Au/TiO₂ NTs exhibited much higher photocurrent density and the photoconversion efficiency of Au decorated TiO₂ NTs was about 2.05 times greater than that of bare TiO₂ NTs. Besides, the PL intensity of Au/TiO₂ NTs was much lower than that of TiO₂ NTs, revealing a decrease in charge carrier recombination. The prepared Au/TiO₂ NTs exhibited superior photoelectrocatalytic activity and stability in the degradation of MB under simulated solar light irradiation. The synergy effect between nanotubular structures of TiO₂ and uniformly dispersed Au nanoparticles, as well as the small bias potential and strong interaction between Au and TiO₂, facilitated the Au plasmon-induced charge separation and transfer, which lead to highly efficient and stable photoelectrocatalytic activity.     

Preparation of waste-based Cu–Cu2O/SiO2 photocatalyst from serpentine tailings and waste printed circuit boards and photoreduction of Cr(VI)

In China, a large amount of serpentine tailings and waste printed circuit boards (WPCBs) are produced every year. Serpentine tailings contain about 43% SiO₂ and WPCBs contain about 20% Cu. Reusing their resources can not only solve the problem of environmental pollution, but also produce certain economic benefits. In this study, waste-based SiO₂ support, waste-based Cu–Cu₂O and Cu–Cu₂O/SiO₂ photocatalyst were prepared using serpentine tailings and WPCBs as Si and Cu sources. The waste-based SiO₂ of 750 nm particle size was obtained by precipitation of 0.7 mol/L Na₂SiO₃ solution from the serpentine tailings and its specific surface area reached 57.72 m²/g after 600 °C calcination. Cu and the waste-based Cu–Cu₂O were loaded on the waste-based Cu₂O and SiO₂ support, respectively, and the phase structure of the catalysts has not changed by the characterization of SEM, XRD and XPS. The activity of the photocatalytic reduction of Cr (VI) with the waste-based catalysts showed in the following order: Cu₂O < Cu₂O/SiO₂<Cu–Cu₂O < Cu–Cu₂O/SiO₂, inferring by the investigation of photoelectric properties that Cu prevented the recombination of Cu₂O electron-hole pairs, the Cu–Cu₂O dispersed on SiO₂ support surface to obtain a higher specific surface area. The waste-based Cu–Cu₂O/SiO₂ photocatalyst showed no obvious deactivation after 5 cycles. The mechanism revealed that photogenerated electrons are the major reactive species for the photodegradation of Cr (VI). The study indicates that the waste-based Cu–Cu₂O/SiO₂ is potentially a developed, low-cost catalyst from sustainable resources. The production of Cu–Cu₂O/SiO₂ photocatalyst by using WPCBs and serpentine tailings represents the potential usage of waste into valuable material.     

Photocrosslinkable acid urethane dimethacrylates from renewable natural oil and their use in the design of silver/gold polymeric nanocomposites

Castor oil-based acid urethane macromers were prepared and employed for obtaining Ag/Au/polymer nanocomposites. Structure and UV induced photopolymerization of the macromers were investigated by spectral methods. The polymerization rate and the degree of conversion decreased with about 10% in the presence of 2.5 wt.% silver nanoparticles (Ag NPs). For the diacid macromer, the surface plasmon intensity increased with irradiation time (the optical density of the absorption maximum (430 nm) attained 2.3 after 600 s), whereas a diminished efficiency was found for Ag NPs in situ generated. Transmission electron microscopy and X-ray photoelectron spectroscopy confirmed uniform distribution of the spherical nanoparticles (0.6 nm (Ag NPs); 5 nm (Au NPs)) and the appearance of Ag 3d_3/2, Ag 3d_5/2, Au 4f_7/2 and Au 4f_5/2 peaks corresponding to Ag (0) or Au (0). Environmental scanning electron microscope with energy-dispersive X-ray detector, contact angle and mechanical parameters measurements complemented the above observations.     

Synthesis of hollow TiO2@g-C3N4/Co3O4 core-shell microspheres for effective photooxidation degradation of tetracycline and MO

Traditional bulk photocatalysts often experience serious charge recombination and poor visible-light capturing, resulting in inefficient photocatalytic activity. However, proper nanostructure design usually helps to increase the activity of composite photocatalysts. Here, hollow TiO₂@g-C₃N₄/Co₃O₄ core-shell microspheres are first reported. The hollow structure of the heterostructured will directionally separate the photogenerated carriers, and the photogenerated holes transferred to the surface will be further captured by Co₃O₄ to achieve an exposed oxidized surface. The novel multi-stage hollow microspheres can simultaneously achieve effective transfer of photogenerated carriers and extended light absorption. Benefiting from these structural and compositional characteristics, the optimized TiO₂@g-C₃N₄/Co₃O₄ nanospheres have excellent photodegradation activity for tetracycline and MO. Under simulated sunlight, the degradation rates of TC (10 mg/L) and MO (25 mg/L) at 60 min are 91.6% and 97.8%, respectively. At the same time, high activity is maintained after multiple cycles of testing. Possible transfer paths for photogenerated carriers have also been proposed. This work will provide more inspiration for the design of multi-stage hollow photocatalytic systems.