Transfer Of Photoexcited Carriers Research Articles

Halogen-Site Regulation in Cs3Bi2X9 Quantum Dots for Efficient and Selective Oxidation of Benzyl Alcohol Driven by Solar Light.

Sluggish charge kinetics and low selectivity limit the solar-driven selective organic transformations under mild conditions. Herein, an efficient strategy of halogen-site regulation, based on the precise control of charge transfer and molecule activation by rational design of Cs3Bi2X9 quantum dots photocatalysts, is proposed to achieve both high selectivity and yield of benzyl-alcohol oxidation. In situ PL spectroscopy study reveals that the Bi─Br bonds formed in the form of Br-associated coordination can enhance the separation and transfer of photoexcited carriers during the practical reaction. As the active center, the exclusive Bi─Br covalence can benefit the benzyl-alcohol activation for producing carbon-centered radicals. As a result, the Cs3Bi2Br9 with this atomic coordination achieves a conversion ratio of 97.9% for benzyl alcohol and selectivity of 99.6% for aldehydes, which are 56.9- and 1.54-fold higher than that of Cs3Bi2Cl9. Combined with quasi-in situ EPR, in situ ATR-FTIR spectra, and DFT calculation, the conversion of C6H5-CH2OH to C6H5-CH2* at Br-related coordination is revealed to be a determining step, which can be accelerated via halogen-site regulation for enhancing selectivity and photocatalytic efficiency. The mechanistic insights of this research elucidate how halogen-site regulation in favor of charge transfer and molecule activation toward efficient and selective oxidation of benzyl alcohol.

Facet-engineered TiO2 drives photocatalytic activity and stability of supported noble metal clusters during H2 evolution

Metal clusters supported on TiO2 are widely used in many photocatalytic applications, including pollution control and production of solar fuels. Besides high photoactivity, stability during the photoreaction is another essential quality of high-performance photocatalysts, however systematic studies on this attribute are absent for metal clusters supported on TiO2. Here we have studied, both experimentally and with first-principles simulation methods, the stability of Pt, Pd and Au clusters prepared by ball milling on nanoshaped anatase nanoparticles preferentially exposing {001} (plates) and {101} (bipyramids) facets during the photogeneration of hydrogen. It is found that Pt/TiO2 exhibits superior stability than Pd/TiO2 and Au/TiO2, and that {001} facet-based photocatalysts always are more stable than their {101} analogous regardless of the considered metal species. The loss of stability associated with cluster sintering, which is facilitated by the transfer of photoexcited carriers from the metal species to the neighbouring Ti and O atoms, most significantly and detrimentally affects the H2-evolution photoactivity.

Photoexcited Carrier Transfer in CuInS2 Nanocrystal Assembly by Suppressing Resonant-Energy Transfer.

High-density assemblies or superlattice structures composed of colloidal semiconductor nanocrystals have attracted attention as key materials for next-generation photoelectric conversion devices such as quantum-dot solar cells. In these nanocrystal solids, unique transport and optical phenomena occur due to quantum coupling of localized energy states, charge-carrier hopping, and electromagnetic interactions among closely arranged nanocrystals. In particular, the photoexcited carrier dynamics in nanocrystal solids is important because it significantly affects various device parameters. In this study, we report the photoexcited carrier dynamics in a solid film of CuInS2 nanocrystals, which is one of the potential nontoxic substitutes with Cd- and Pb-free compositions. Meanwhile, these subjects have been extensively studied in nanocrystal solids formed by CdSe and PbS systems. A carrier-hopping mechanism was confirmed using temperature-dependent photoluminescence spectroscopy, which yielded a typical value of the photoexcited carrier-transfer rate of (2.2±0.6)×107 s-1 by suppressing the influence of the excitation-energy transfer.

Linkage effect in the bandgap-broken V2O5-GdCrO3 heterojunction by carbon allotropes for boosting photocatalytic H2 production

Refining carrier transfer in bandgap-broken heterojunctions, which consist of two semiconductors with broken bandgaps, is crucial yet highly challenging for photocatalysis. Herein, we incorporated amorphous carbons (AC) into the bandgap-broken V2O5/GdCrO3 heterojunctions, inducing a linkage effect to facilitate photoexcited carrier transfer. The created V-O-C and Cr-O-C bonds in V2O5-AC-GdCrO3 interfaces show almost identical orbital energies to overcome the broken-gap energy barriers at interfaces. The holes at GdCrO3’s valence band and electrons at V2O5’s conduction band tent to migrating toward the carbon ring of amorphous carbon via Cr-O-C and V-O-C bonds, thereby enhancing carrier separation of bandgap-broken V2O5/AC/GdCrO3 heterojunction. By controlling the relative amount of metal-O-C bonds in the interface, the modulation of charge transfer kinetics was also achieved on V2O5/AC/GdCrO3, resulting in ∼7 times higher of H2 generation than V2O5/GdCrO3. The concept could be expanded to the other carbon allotropes, including graphene, carbon nanotube, and graphdiyne conjugated structures, demonstrating a universal strategy in reaching optimal charge transfer of broken-bandgap heterojunctions for photocatalytic H2 production.

Charge transfer mechanism through S-scheme heterojunction in in-situ synthesized TiO2/Fe-doped hydroxyapatite for improved photodegradation of xanthate

The heterojunction structure of the photocatalyst composite, which necessitates a robust interface and sufficient contact areas, holds the key to obtaining high charge carrier migration efficiency. Here, a novel composite, TiO2 nanoparticles/Fe-doped hydroxyapatite (TONPs/FH_CS), is fabricated using a two-step synthetic technique, in which FH_CS is synthesized from artificial converter slag enriched with Fe and Ca. The unique nanorod@plate structure of FH_CS enables the uniform immobilization of TONPs onto FH_CS. Thereby, an n-n type heterojunction exhibits a highly intimate Ti-O-Fe heterointerface. Kelvin probe testing demonstrates the formation of an interfacial electric field oriented from FH_CS to TONPs, which serves as the driving force for interfacial electron transfer through the Ti-O-Fe channels. The photoacoustic signals provide information on electron trap levels and densities, indicating the formation of the electron transfer channels. •O2– and •OH species are responsible for being the active species in this system. A photoexcited carrier transfer pathway exhibiting an S-scheme mechanism with high separation efficiency significantly enhances the utilization of charge carriers in each phase. Thus, improved xanthate degradation has been achieved using a heterojunction containing a photocatalyst derived from industrial solid waste. This work demonstrates the significant potential of steel-making byproduct utilization in industrial wastewater treatment.

NiO@Carbon quantum dots S-scheme heterojunction as a light-activated oxidase mimic for Cu2+ colorimetric detection

Light-activated oxidase mimics have a wide application prospect in environment, detection, medicine and other fields because of its stability, environmental friendliness and high activity. Here a S-scheme heterojunction formed by NiO nanosheets modified with carbon quantum dots (CQDs) is prepared as a light-activated oxidase mimic. The modification of CQDs expands the light absorption range of NiO, while NiO as a matrix improves the dispersion of CQDs. Moreover, at the contact interface a S-scheme heterojunction forms, accelerating the separation of photoexcited electrons and holes under the built-in electric field and band bending. The unique transfer of photoexcited carriers maintains high oxidation and reduction activity of NiO@CQDs, improving its photocatalytic activity. NiO@CQDs can oxidize o-phenylenediamine (OPD) to yellow under light, and when Cu2+ was present in the solution, this colorimetric reaction was inhibited. Therefore, NiO@CQDs could be used for colorimetric detection of Cu2+, with a wide linear range of detection (0–0.1 µM, 0.1–1 µM, 1–10 µM, 10–100 µM), low detection limit (0.024 μM), good selectivity and stability.

Construction of Pt@BiFeO3 Xerogel-Supported O-g-C3N4 Heterojunction System for Enhanced Visible-Light Activity towards Photocatalytic Degradation of Rhodamine B

Synthetic organic pigments from the direct discharge of textile effluents are considered as colossal global concern and attract the attention of scholars. The efficient construction of heterojunction systems involving precious metal co-catalysis is an effective strategy for obtaining highly efficient photocatalytic materials. Herein, we report the construction of a Pt-doped BiFeO3/O-g-C3N4 (Pt@BFO/O-CN) S-scheme heterojunction system for photocatalytic degradation of aqueous rhodamine B (RhB) under visible-light irradiation. The photocatalytic performances of Pt@BFO/O-CN and BFO/O-CN composites and pristine BiFeO3 and O-g-C3N4 were compared, and the photocatalytic process of the Pt@BFO/O-CN system was optimized. The results exhibit that the S-scheme Pt@BFO/O-CN heterojunction has superior photocatalytic performance compared to its fellow catalysts, which is due to the asymmetric nature of the as-constructed heterojunction. The as-constructed Pt@BFO/O-CN heterojunction reveals high performance in photocatalytic degradation of RhB with a degradation efficiency of 100% achieved after 50 min of visible-light irradiation. The photodegradation fitted well with pseudo-first-order kinetics proceeding with a rate constant of 4.63 × 10−2 min−1. The radical trapping test reveals that h+ and •O2− take the leading role in the reaction, while the stability test reveals a 98% efficiency after the fourth cycle. As established from various interpretations, the considerably enhanced photocatalytic performance of the heterojunction system can be attributed to the promoted charge carrier separation and transfer of photoexcited carriers, as well as the strong photo-redox ability established. Hence, the S-scheme Pt@BFO/O-CN heterojunction is a good candidate in the treatment of industrial wastewater for the mineralization of organic micropollutants, which pose a grievous threat to the environment.

Recent Advances in Efficient Photocatalysis via Modulation of Electric and Magnetic Fields and Reactive Phase Control.

The past several years has witnessed significant progress in enhancing photocatalytic performance via robust electric and magnetic fields' modulation to promote the separation and transfer of photoexcited carriers, and phase control at reactive interface to lower photocatalytic reaction energy barrier and facilitate mass transfer. These three research directions have received soaring attention in photocatalytic field. Herein, recent advances in photocatalysis modulated by electric field (i.e., piezoelectric, pyroelectric, and triboelectric fields, as well as their coupling) with specific examples and mechanisms discussion are first examined. Subsequently, the strategy via magnetic field manipulation for enhancing photocatalytic performance is scrutinized, including the spin polarization, Lorentz force, and magnetoresistance effect. Afterward, materials with tailored structure and composition design enabled by reactive phase control and their applications in photocatalytic hydrogen evolution and carbon dioxide reduction are reviewed. Finally, the challenges and potential opportunities to further boost photocatalytic efficiency are presented, aiming at providing crucial theoretical and experimental guidance for those working in photocatalysis, ferroelectrics, triboelectrics, piezo-/pyro-/tribo-phototronics, and electromagnetics, among other related areas.

Interfacial configuration and mechanism insights of an all-solid-state Z-scheme BaTiO3/Bi/Bi2O3 heterojunctions for rapid removal of tetracycline antibiotics

Photocatalytic technology based on efficient-economic heterojunction catalysts has been considered a promising approach to remove the discharged tetracycline (TC) antibiotic residues in contaminated water. However, unveiling an effective interface configuration with a clear mechanism is still the toughest challenge for heterojunction photocatalysts. Through a facile route of hydrothermal and heat treatment for the first time, herein, we reported an all-solid-state Z-scheme heterojunction of BaTiO3/Bi/Bi2O3 (BT/Bi/BO) with a conspicuous light response and efficient photo-excited carrier kinetics (high separation and redox ability). It performed a stable and ultrahigh photocatalytic activity toward removing TC, which can be quickly degraded in a few minutes. Density functional theory calculation on heterogeneous interface confirmed that the metallic Bi at the interlayer played a critical role in the excellent photocatalytic performance. The interlayer Bi not only promoted the adhesion between BT and BO to enhance the structural stability, but also had a strong interaction with O atoms of BT to reduce the band gaps to improve the light response. Moreover, its p band located in the band gaps can assist the Z-scheme transfer of photo-excited carriers under an interfacial built-in electronic field of the heterojunction. Therefore, this work provides a new perspective and deep understanding of the configuration and interfacial mechanism of Z-scheme heterogeneous photocatalysts for the removal of antibiotics.

Engineering covalently integrated COF@CeO2 Z-scheme heterostructure for visible light driven photocatalytic CO2 conversion

The porphyrin-based covalent organic frameworks (COFs) are promising candidates for photocatalytic CO2 conversion account for their long-range ordered mesopores and excellent semiconducting properties, but the insufficient oxidative capacity of valence band is less efficient for photooxidation of H2O, which hinders the photocatalytic performance. Herein, the stable organic–inorganic Z-scheme heterostructure was constructed through covalently connecting COF-366-Fe consisting of Fe-porphyrin and terephthaldehyde units with CeO2 by Schiff base reaction with an in-situ reaction strategy. The COF-366-Fe@CeO2 core–shell Z-scheme heterojunction not only effectively integrated the light-harvesting capability, active metal centers of COF-366-Fe and strong oxidation ability of CeO2, but also promoted the separation and transfer of photoexcited carriers. The as-prepared COF-366-Fe@CeO2 exhibited a photocatalytic CO yield of 66.2 μmol g−1 in 8 h with a 99 % selectivity under the visible light irradiation without additional photosensitizers and sacrificial agents, which was far superior to COF-366-Fe and CeO2. The remarkable promoted performance is ascribed to the covalently contact Z-scheme heterojunction interface, which benefited to facilitate the separation of photoexcited electron-hole pairs, as confirmed by the results of electronic paramagnetic resonance, time-resolved photoluminescence and in-situ XPS. This study provides an idea for designing highly-effective COF-based photocatalysts for artificial photosynthesis.

Highly Selective Photocatalytic Oxidation Biomass Valorization Over Nb2O5/g‐C3N4Heterojunction

The selective biomass conversion of 5‐hydroxymethylfurfural (HMF) to 2,5‐diformylfurane (DFF) through photocatalysis is of immense importance and has attracted much interest recently. However, its selectivity and conversion are still limited at present due to the lack of efficient photocatalysts to controllably activate the alcohol hydroxyl groups. Herein, Nb2O5/g‐C3N4type‐II heterojunction photocatalysts to restrain the over‐oxidation are developed, which successfully adjust the active oxygen species and enhance the separation and transfer of photoexcited carriers. The system achieves selective oxidation of HMF to DFF with high selectivity (>99%) and conversion (53%) via the inhibition of hydroxyl radicals (·OH) production arising from the decomposition of H2O2. Moreover, h+is the main active species for photocatalytic selective oxidation of HMF, and ·O2−is the second for that. Herein, it offers an effective strategy to effectively improve the high‐selective conversion of biomass derivatives into high‐value‐added products.

In-depth photocarrier dynamics in a barrier variable iron-oxide and vertically aligned reduced-graphene oxide composite

A key requirement for semiconductors operating in light-harvesting devices, is to efficiently convert the absorbed photons to electronic excitations while accommodating low loss pathways for the photogenerated carrier’s transport. The quality of this process corresponds to different relaxation phenomena, yet primarily it corresponds to minimized thermalization of photoexcited carriers and maximum transfer of electron-hole pairs in the bulk of semiconductor. However, several semiconductors, while providing a suitable platform for light-harvesting applications, pose intrinsic low carrier diffusion length of photoexcited carriers. Here we report a system based on a vertical network of reduced graphene oxide (rGO) embedded in a thin-film structure of iron oxide semiconductor, intended to exploit fast electron transport in rGO to increase the photoexcited carrier transfer from the bulk of the semiconductor to rGO and then to the external circuit. Using intermodulation conductive force microscopy, we locally monitored the fluctuation of current output, which is the prime indication of successful charge transfer from photoexcited semiconductor to rGO and efficient charge collection from the bulk of the semiconductor. We reveal the fundamental properties of vertical rGO and semiconductor junction in light-harvesting systems that enable the design of new promising materials for broad-band optical applications.

The seeds and homogeneous nucleation of photoinduced nonthermal melting in semiconductors due to self-amplified local dynamic instability.

Laser-induced nonthermal melting in semiconductors has been studied over the past four decades, but the underlying mechanism is still under debate. Here, by using an advanced real-time time-dependent density functional theory simulation, we reveal that the photoexcitation-induced ultrafast nonthermal melting in silicon occurs via homogeneous nucleation with random seeds originating from a self-amplified local dynamic instability. Because of this local dynamic instability, any initial small random thermal displacements of atoms can be amplified by a charge transfer of photoexcited carriers, which, in turn, creates a local self-trapping center for the excited carriers and yields the random nucleation seeds. Because a sufficient amount of photoexcited hot carriers must be cooled down to band edges before participating in the self-amplification of local lattice distortions, the time needed for hot carrier cooling is the response for the longer melting time scales at shorter laser wavelengths. This finding provides fresh insights into photoinduced ultrafast nonthermal melting.

Promoting photocatalytic degradation of tetracycline over in-situ grown single manganese atoms on polymeric carbon nitride

Introducing single-atom metals into polymeric carbon nitride (PCN) framework is a promising strategy to offer more active sites along with pollutant degradation kinetics. Herein, single manganese atoms decorated PCN (denoted as MCN) was fabricated via a straightforward in-situ thermopolymerization strategy using urea as PCN precursor and manganese acetylacetone as manganese (Mn) source. The as-synthesized optimal sample MCN-2 exhibits legible monatomic Mn sites on PCN framestructure and enhanced specific surface area (122.4 m2·g−1). The monatomic Mn introduced via the Mn-N/O coordination is demonstrated to be able to narrow the bandgap and facilitate separation and transfer of photo-excited carriers, which has a salutary effect on visible-light harvesting and MCN utilization. Consequently, the MCN-2 exerts a superior pseudo-first-order kinetic rate constant k of 0.041 min−1 in visible-light-driven TC photodegradation, with ca. 13-fold higher than that of the pristine PCN. Further, the intermediates and reactive oxygen species (1O2, h+ and •O2–) generating in the TC photodegradation process are experimentally manifested and a plausible mechanism for TC degradation over MCN is proposed. This work not only proves the efficacy of MCN in photodegradation of TC but expands Mn to other single-atom metals for pollutant removal.

Construction of flower-like Ag/AgBr/BiOBr heterostructures with boosted photocatalytic activity

• The powerful interaction between AgBr and BiOBr has been proved. • The separation efficiency of photogenerated carriers has been enhanced. • The level of O 2 – is significantly increase. • Flower-like AgBr/BiOBr exhibits higher activity than BiOBr. Construction of heterostructures is a valid channel to tune the activity of the photocatalyst. In this work, Ag/AgBr/BiOBr heterostructures were in-situ built by a precipitation method. The constructed heterojunctions were carefully characterized by some analytic methods. The characterization results show that construction of heterojunctions can promote the separation of photoactivated carriers. Rhodamine B (RhB) was used to evaluate photocatalytic activity under simulated sunlight. When the molar ratio of AgBr/BiOBr is 2%, the heterostructures prepared possess the highest photocatalytic activities. Photocatalytic activity of the 2% sample is 2-fold of that of BiOBr. Moreover, the sample has outstanding stability. In view of the experimental results, a mechanism for separation and transfer of photoexcited carriers was elaborated.

Large negative thermal quenching of yellow luminescence in non-polar InGaN/GaN quantum wells

Large negative thermal quenching (NTQ) of the yellow luminescence (YL) for a temperature increase from 5 to 300 K is observed in non-polar InGaN/GaN quantum well (QW) samples due to the thermal migration of carriers from the InGaN QW layers to the GaN barrier layers for the first time. Such an unusual phenomenon happens only when the carriers are optically excited inside the QW layers, providing solid evidence for the occurrence of thermal transfer of photoexcited carriers from the QW layers to the GaN barrier layers. A simple model considering the thermal transfer of carriers is proposed to interpret the observed NTQ phenomenon. The thermal activation energy of the carriers is determined by fitting the reciprocal temperature dependence of the YL intensity in the Arrhenius plot with the model.

Morphology and Phase Engineering of MoS2 Cocatalyst for High-Efficiency Hydrogen Evolution: One-Step Clean Synthesis and Comparative Studies

Effective separation and transfer of photoexcited carriers are essential for photocatalysis, which could be optimized by the rational design of morphology and phase structure. Herein, using NH4HCO3 as intercalating and orienting agents, few-layer vertical-standing multiphasic MoS2 nanosheets (VM-MoS2) were successfully constructed along the longitudinal axis of CdS nanorods via a green hydrothermal method. The growth mechanism of VM-MoS2 on CdS nanorods was demonstrated to include the competitive adsorption of HCO3– and Mo7O246– anions on the protonated CdS, and the intercalation of NH4+ cations. Moreover, the impacts of the morphology and phase structure of the MoS2 cocatalyst on the photocatalytic H2 evolution (PHE) performance of CdS were carefully compared. It is found that the VM-MoS2 nanosheets can not only expose abundant active sites, but also allow the supporter to harvest the light effectively. Additionally, the metallic 1T-MoS2 in VM-MoS2 would help the interface transfer of photogenerated electrons and act as photoelectron entrepots and catalytically active sites for H2 evolution. With the VM-MoS2 cocatalyst, the as-synthesized CdS@VM-MoS2 shows an outstanding PHE rate of ∼40.1 mmol·h–1·g–1 under visible-light irradiation. Interestingly, integrating with the 2H-MoS2 phase will make the metastable 1T-MoS2 more stable, leading to the exceptional photostability of CdS@VM-MoS2 nanocomposite.

Efficient carrier transfer route via the bridge of C60 particle to TiO2 nanoball based coverage layer enables stable and efficient cadmium free GeSe photocathode for solar hydrogen evolution

Sufficient passivation/coverage and transfer of photoexcited carriers are the key factors in creating efficient and stable photoelectrochemical water splitting electrodes. In this work, the photoelectrochemical properties of Cd-free GeSe micro air brick-based photocathodes were systematically investigated by surface and interface analyses. It was found that carrier accumulation at the interface between Pt catalysts and the surface of the GeSe photocathode would induce the detachment of Pt catalysts and therefore degrade the photoelectrochemical current. Fortunately, we found that introducing a C60 particle intermediate helped build a bridge between the Pt catalysts and TiO2 balls, accelerating electron transfer, avoiding the self-reduction of TiO2 balls, and decreasing the accumulation of photoexcited carriers at interfaces. The GeSe micro air brick-based photocathode covered with Cd-free Pt/C60 pat.-TiO2 ball composite materials exhibited a significantly enhanced long-term stability of 60 h. Based on such a Pt/C60 pat.-TiO2 ball/GeSe photocathode, a GeSe-BiVO4 tandem cell for unbiased overall solar water splitting was first reported. The tandem cell presented a benchmark solar to hydrogen (STH) conversion efficiency of 1.37 % with appreciably long time stability over 12 h, indicating the great competitiveness of the GeSe-based photoelectrode among the emerging photoelectrodes for solar hydrogen evolution.

2D/2D heterostructure of ultrathin BiVO4/Ti3C2 nanosheets for photocatalytic overall Water splitting

Photocatalytic overall water splitting is a promising environmental friendly technique to convert solar energy into hydrogen (H2) and oxygen (O2). Here, BiVO4 ultrathin nanosheets is found to disintegrate pure water into H2 and O2 simultaneously under simulated solar light irradiation without sacrificial reagents. And a novel 2D/2D BiVO4/Ti3C2 composites is successfully synthesized through electrostatic interaction between BiVO4 and Ti3C2 nanosheets. Because the unique 2D/2D heterojunction possesses large interface contact area and quite short charge transport distance, BiVO4/Ti3C2 displays much higher photoexcited carrier transfer and separation efficiency and ultimately exhibits remarkable photocatalytic overall water splitting activity. This work may provide the first experimental confirmation of ultrathin BiVO4 nanosheets with an ability of photocatalytic overall water splitting, and the 2D/2D combination between BiVO4 and Ti3C2 is an effective way for further improving the activity, which may provide guidance for designing efficient water splitting photocatalysts in the future.

Novel Co3O4 @ CoFe2O4 double-shelled nanoboxes derived from Metal–Organic Framework for CO2 reduction

Fabrication heterojunction semiconductors with proper band alignments and reasonable morphologies for photocatalytic CO2 reduction are eliciting increased attention. Hence, a novel Z-scheme heterojunction of Co3O4 @ CoFe2O4 hierarchical hollow double-shelled nanoboxes was designed via Metal–Organic Framework engaged templating method and hydrothermal reaction procedure. An online spectral mean has been employed to study the reaction process in this work. The structural and optical properties of Co3O4 @ CoFe2O4 was comprehensively identified by a series of analytical characterizations. The characterization results depicted that Co3O4 @ CoFe2O4 hierarchical hollow double-shelled nanoboxes were constructed, and the surfaces of Co3O4 nanocubes were covered by CoFe2O4 Nanosheets (NSs). In general, the unique Z-scheme heterojunction of as-synthesized materials facilitated the interfacial separation and transfer of photoexcited carriers. And hierarchical hollow structure offered larger surface area, increased CO2 adsorption properties and exposed more active sites. The Co3O4 @ CoFe2O4 showed the optimum CO2 photo-reduction activities, the CH4 and CO production rates were 2.06 μmol h−1 and 72.2 μmol h−1 respectively. This work validated that Co3O4 @ CoFe2O4 is a powerful photocatalyst for CO2 reduction, and this hybrid structures can also pave an insight into the development of novel recyclable heterojunctions to practical application.