Photoelectrocatalytic Reduction Research Articles

Photoelectroreduction CO2 to Ethanol Over BiFeO3 with Synergistic Effect of Self‐Polarization and External Electric Field

The exploitation of semiconductor self‐polarization is an effective mean of improving the efficiency of electron utilization. In this work, the synthesis of BiFeO3 (BFO) samples with varying photoelectric properties is achieved by modulating the concentration of KOH. The experimental results reveal that BFO‐4 (4 m KOH) has excellent carrier efficiency. Interestingly enough, the ethanol yield of up to 7.05 μmol cm−2 h−1 in the photoelectrocatalytic process, which is 1.4 times than that of single electrocatalysis. Based on the characterization data, the external electric field forms a multi‐electric field coupling in the BFO (external electric field can enhance the self‐polarization electric field), which enhances charge separation efficiency and facilitates surface reactions, and the CO2 reduction performance is improved. Finally, the free energy in the key step of CC coupling on the surface of BiFeO3 is calculated by DFT. This study offers a valuable reference for the application of ferroelectric materials in the photoelectrocatalytic reduction of CO2 and the design of catalysts for C2+ products.

Building organic-inorganic heterojunction NiCo2O4/h-BN toward artificial photosynthesis—Boron as hole

To convert CO2 and water into organic chemicals via photoelectrocatalytic (PEC) reduction of CO2 under mild conditions is considered to be one of promising methods to address a series of problems like climate change and energy crisis caused by over-emission of CO2. Herein, the organic-inorganic heterojunctions were designed and fabricated by using organic h-BN and inorganic NiCo2O4 as precursors. The optimal NiCo2O4@h-BN-6 heterojunction exhibited impressive performance in CO2 reduction, yielding C2+ chemicals with 100 % selectivity in a rate of 28.5 μM cm−2 h−1. This phenomenon is attributed to the structural feature of three active sites of nitrogen in a unique hexacycle like benzene, which benefit the carbon-carbon coupling among the intermediates. The first observed *N-H species suggest that the N sites can adsorb protons and electrons and convert them into highly active hydrogen atoms. The verification experiments demonstrate that the material will oxidize intermediates to acetic acid where boron atoms are presented as holes in semiconductor. The isotopic labeling experiments of 13CO2 and H218O verified that the products were derived from CO2 and water. The key active intermediates such as *CHO, *=CO, and *COCHO in the synthetic process of C2+ products had been confirmed by operando FTIR spectra and DFT calculations.

Synthesis of isolated ZnO nanorods on introducing g-C3N4 for improved photoelectrocatalytic methanol production by CO2 reduction

The photoelectrocatalytic (PEC) CO2 reduction into fuels has been developed as a prospective approach to resolve the environmental and energy concerns. Herein, a composite catalyst comprising ZnO nanorods dispersed on the g-C3N4 surface (g-C3N4/ZnO) was successfully obtained by simple ZnO seed layer formation and then hydrothermal processes. The synthesized and characterized g-C3N4/ZnO catalytic composite showed 2.8 times enhanced photocurrent density at −1 V applied potential than the bare g-C3N4. The g-C3N4/ZnO catalyst exhibited 2.86 times enhanced the PEC CO2 reduction to methanol than the prepared bare ZnO catalyst. The catalyst’s enhanced the PEC CO2 reduction performance was ascribed to the high surface area, and higher generation and lower recombination of e−/h+ pairs. For the first time, this study showed the enhanced methanol production by the PEC reduction of CO2 over the prepared g-C3N4/ZnO catalytic composite.

Efficient CO2 reduction to C2 products in a Ce-TiO2 photoanode-driven photoelectrocatalysis system using a Bnanometer Cu2O cathode

Excessive emission of CO2 into the atmosphere has caused significant environmental issues. Photoelectrocatalytic (PEC) reduction of CO2 is an effective method that combines the benefits of both photo- and electrocatalysis. This process effectively minimizes CO2 emissions, enhances the efficiency of CO2 reduction, and diminishes energy consumption during the reduction process. In this work, we have successfully developed a photoelectrochemical (PEC) system, integrating a Ce-doped TiO2 film as the photoanode and Cu2O as the dark cathode, in which the 4 % Ce-TiO2 film photoanode demonstrated the best performance. Electrochemical performance data revealed that the Cu2O catalysts, characterized by their octahedral geometry that optimally presents active sites for CO2 reduction, displayed superior activity in converting CO2. Through a straightforward hydrothermal synthesis, we crafted three-dimensional, flower-like TiO2 thin films. The strategic incorporation of cerium into the TiO2 matrix not only enhanced the material's crystallinity but also resulted in a uniform and compact morphology. This modification significantly narrowed the band gap of TiO2, thereby boosting its photocatalytic capabilities. In the system where a 4 % Ce-TiO2 thin film photoanode was used to drive the PEC reduction of CO2, the octahedral Cu2O catalyst demonstrated the highest selectivity for C2 products. This occurred at a reaction voltage of −1.4 V vs. RHE, resulting in a total Faraday efficiency of 67.33 %. Notably, this Faraday efficiency is double the one produced from the electrocatalytic (EC) system. This work demonstrates that the use of a 4 % Ce-TiO2 film as a photoanode is able to solve the photocorrosion problem of the Cu2O catalyst while employing a photovoltaic combination to enhance the selectivity to C2 products.

One-dimensional nanostructure arrays with Schottky Junction enhanced charge separation for the photoelectrocatalytic selective removal of Uranium from wastewater

The photoelectrocatalytic reduction of soluble U(VI) to relatively insoluble U(IV) is a promising method for uranium wastewater treatment. However, the strong reliance on sacrificial agents and an inert atmosphere due to the rapid charge reorganization remains a great challenge. The construction of an inner electrical field at a heterojunction interface accompanied by an external electric field provides a promising strategy for enhancing charge transfer. Herein, a photoelectrode was proposed by in-situ coating nano-TiO2 cone arrays (NTCA) on a titanium mesh, and used for uranium removal from complex effluents under air conditions without sacrificial agents. The enhanced spatial charge separation driven by the Schottky junction built-in electric field and an external bias voltage, coupled with rapid fluid diffusion, granted the photoelectrode an outstanding photoelectrocatalytic uranium removal performance with photocurrent densities of up to 3 mA cm−2 at −0.55 VAg/AgCl. The impressive uranium removal performance was maintained in a wide range of chemical conditions, as well as in real seawater and industrial wastewater. Theoretical calculation revealed that uranyl ions were confined on the NTCA surface as [UO2(H2O)5]2+, further reduced to UO2. This work demonstrated a viable route for uranium separation from aqueous solutions with inexhaustible solar energy and minimal electrical energy.

Photoelectrocatalytic Reduction of CO2 to CO via Cu2O/C/PTFE Nanowires Photocathodes

AbstractThe consumption of fossil fuels releases large amounts of carbon dioxide (CO2) in the atmosphere, causing a serious greenhouse effect. Photoelectrochemical (PEC) reduction of CO2 to chemical fuels is an effective way to alleviate the current energy and environmental crisis. However, it is still difficult to rationally design efficient PEC CO2 reduction photocathodes. Cuprous oxide (Cu2O) is a promising photocathode material, but its surface is susceptible to the accumulation of photogenerated electrons leading to corrosion and activity reduction, and is accompanied by hydrogen evolution reaction (HER), both of which lead to the overall low conversion efficiency of CO2 reduction by Cu2O. In this study, the PEC CO2 conversion efficiency was improved by the synergistic effect of the C electron transport layer to accelerate the electron transfer to alleviate the Cu2O corrosion problem and the polytetrafluoroethylene (PTFE) hydrophobic layer to inhibit the HER. The test showed that the CO yield of Cu2O/C/PTFE at the optimum potential (−0.7 V vs. RHE) was 54.6 μmol cm−2 h−1, which was 3.2 times higher than that of pure Cu2O. This study provides a facile strategy for constructing an efficient photocathode with great potential for CO2 reduction.

Enhanced photo-electro catalytic CO2 conversion using transition metal doped TiO2 nanoparticles

The Fe, Co, and Ni-doped TiO2 were synthesised by sol–gel process, and the nanomaterials were coated on electrodes through a slurry with Nafion. This study aims to use prepared nanoparticles of Fe, Co, and Ni-doped TiO2 to enhance the photo-electrocatalytic conversion of CO2. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), and electrochemical analyses were utilized to characterise the doped and undoped TiO2 nanoparticles. Transmission electron microscopy (TEM) studies revealed that the nanomaterials had an average size below 20 nm. Tauc plot analysis for optical absorption studies shown a reduction in band gap when doped with Fe, Co and Ni, with the most significant decrease observed for Fe-doped TiO2, following the order Fe < Co < Ni. Electrochemical CO2 conversion efficiencies were investigated through cyclic voltammetry (CV) curves, electrochemical impedance spectroscopy (ESI), and linear sweep voltammetry (LSV) studies. The results were analysed based on various scan rates and photo exposure, indicating superior performance for Fe-TiO2, aligning with the observed band gap trends. Gas chromatography (GC) analysis of the reduction products revealed the generation of hydrocarbons, with Fe-TiO2 exhibiting the most favourable outcomes. This research provides valuable insights into tailoring TiO2 nanoparticles for efficient photo-electro catalytic reduction of CO2.

Photoelectrochemically converting CO2 over Z-scheme heterojunction CoPc/K7HNb6O19 with high Faraday efficiency

Photoelectrochemically converting CO2 into the high value-added chemicals and fuels is a hopeful sustainable energy conversion and storage road to alleviate the energy crisis and global warming. In this study, CoN-x Z-scheme heterojunctions were prepared by coupling CoPc with K7HNb6O19 rich in oxygen vacancy with a low-temperature calcination, and used for photoelectrocatalytic (PEC) reduction of CO2 to CO. The prepared heterojunctions demonstrate Faraday efficiency of >90 % and TOF values over a wide voltage range (−0.65 ∼ −1 V vs. RHE). The superior PEC CO2 reduction performance is mainly attributed to the designed Z-scheme heterojunction, which endows a built-in electric field to the interface of the two semiconductors, benefiting the separation of electrons and holes greatly. Additionally, the oxygen vacancy from K7HNb6O19 provides an alternative pathway for CO2 adsorption and activation, and simultaneously the incorporated K7HNb6O19 inhibits the aggregation of cobalt phthalocyanine molecules, which is beneficial for the stability of PEC catalysts. Density-functional-theory (DFT) calculation also elucidates a favorable CO2 activation energy over CoPc coupling oxygen-vacancy-rich K7HNb6O19 heterojunctions. This work may provide a viable pathway for the rational designing of efficient PEC systems to reduce CO2 to valuable fuels.

Photoelectrocatalytic Reduction of Cr(VI) in Wastewater with a CuBi2O4 Thin Film Photocathode

Photoelectrocatalytic approaches show promise for contaminate removal in wastewater through redox reactions. However, the direct treatment of very low concentration heavy metals is a challenging task. Copper bismuth oxide is considered as a potential photocathode material due to its appropriate bandgap width and excellent light absorption properties. In this work, we utilize copper bismuth oxide photoelectrodes with micrometer-scale pores to achieve the efficient and complete reduction of micromolar-level hexavalent chromium(VI) in wastewater. In a continuous 180 min experiment, the reduction rate of 5 µM hexavalent chromium reached 97%, which is an order lower than the drinking standard. Such a process was facilitated by the unique hierarchical microstructure of the oxide thin film and the porous morphology. On the other hand, the structural evolution during the operation was analyzed. A surface passivation was observed, suggesting the possible long-term practical application of this material. This study serves as an important reference for the application of photoelectrocatalysis in addressing Cr(VI) pollution in wastewater, with implications for improving water quality and environmental protection.

Triazine-COF@Silicon nanowire mimicking plant leaf to enhance photoelectrocatalytic CO2 reduction to C2+ chemicals

Triazine-COF@Silicon nanowire mimicking plant leaf to enhance photoelectrocatalytic CO2 reduction to C2+ chemicals

In Situ Preparation of Mo:BiVO4 Photoanodes Coupled with BiOBr Cathode for Efficient Photoelectrocatalytic CO2 Reduction Performance

Photoanode‐driven photoelectrocatalytic (PEC) reduction of CO2 is an ideal way for solving problems such as the greenhouse effect and environmental crisis. In this study, a one‐step hydrothermal method is successfully used for the preparation of BiVO4 films doped with different mass fractions of Mo. In the results, it is shown that when Mo is doped at 1.5 wt%, photocurrent densities of up to 4.11 mA cm−2 are obtained, 3.36 times greater than those of undoped BiVO4, and there is a marked cathodic shifting of water oxidation reaction initiation potential. Subsequently, coupling it with the BiOBr nanosheet cathode, the generated CH3OH rate reaches 45.67 μmol L−1 h−1 cm−2 at a low applied voltage of 1.2 VRHE, with a Faraday efficiency of 60.68% for PEC CO2 reduction. This work is important for Bi‐based thin‐film self‐assembly coupled with PEC CO2 systems.

Exploiting hot electrons from a plasmon nanohybrid system for the photoelectroreduction of CO2

Plasmonic materials convert light into hot carriers and heat to mediate catalytic transformation. The participation of hot carriers (photocatalysis) remains a subject of vigorous debate, often argued on the basis that carriers have ultrashort lifetime incompatible with drive photochemical processes. This study utilises plasmon hot electrons directly in the photoelectrocatalytic reduction of CO2 to CO via a Ppasmonic nanohybrid. Through the deliberate construction of a plasmonic nanohybrid system comprising NiO/Au/ReI(phen-NH2)(CO)3Cl (phen-NH2 = 1,10-Phenanthrolin-5-amine) that is unstable above 580 K; it was possible to demonstrate hot electrons are the main culprit in CO2 reduction. The engagement of hot electrons in the catalytic process is derived from many approaches that cover the processes in real-time, from ultrafast charge generation and separation to catalysis occurring on the minute scale. Unbiased in situ FTIR spectroscopy confirmed the stepwise reduction of the catalytic system. This, coupled with the low thermal stability of the ReI(phen-NH2)(CO)3Cl complex, explicitly establishes plasmonic hot carriers as the primary contributors to the process. Therefore, mediating catalytic reactions by plasmon hot carriers is feasible and holds promise for further exploration. Plasmonic nanohybrid systems can leverage plasmon’s unique photophysics and capabilities because they expedite the carrier’s lifetime.

Efficient photoelectrocatalytic reduction of CO2 to formate via Bi-doped InOCl nanosheets

Converting CO2 into useful substances is an important approach to address the challenge of reducing CO2 emissions and combating climate change. Compared with the traditional process, photoelectrocatalytic CO2 reduction has great potential to solve the problem of CO2 emission. In this work, Bi-doped InOCl cathode catalysts were prepared by a two-step calcination process, and they demonstrated efficient catalytic activity for the reduction of CO2 to formate. The inclusion of bismuth (Bi) in InOCl resulted in improved catalytic performance compared to the native InOCl catalyst. Specifically, the highest formate selectivity can be observed at −0.9 V vs RHE with a Faraday efficiency of 89.9% and the product rate of 101.41 μmol h–1cm–2 when the Bi doping amount is 5%, representing approximately 2 and 3 times the values obtained with native InOCl, respectively. The experimental results indicate that Bi doping promotes the formation of {001} crystalline surfaces in InOCl, while increasing the specific surface area and the availability of more active sites for CO2 reduction. This work holds significant potential for further advancements in the field of photoelectrocatalytic reduction of CO2.

Disentangling the Role of Ag‐Based Nanocorals as Efficient Cocatalyst over CuBi2O4 Photocathodes Toward Hydrogen Evolution Reaction

CuBi2O4 is one of the most studied potential candidates for photoelectrocatalytic solar fuel generation, from H2 production, to CO2 reduction, or even N2 fixation. Hence, understanding its performance and catalytic behavior is key to use this material under real working conditions. Herein, Ag nanocorals are successfully deposited over CuBi2O4 photocathodes for enhancing its performance as a promising candidate for photoelectrocatalytic reduction reactions. An in‐depth study of this novel structure through a combination of several materials’ characterization techniques, confirming the tetragonal structure and the stoichiometric proportion of the elemental components, is presented. In addition, the different charge transfer processes and catalytic mechanisms behind the performance of Ag‐decorated CuBi2O4 photocathodes are unveiled through a combination of electrochemical impedance spectroscopy and transient absorption spectroscopy. The combination of these advanced spectroscopies reveals that Ag is acts as a true catalyst, enhancing the charge extraction and decreasing the charge accumulation and the recombination at the CuBi2O4 surface, thus boosting the photocathode performance.

β-Bi2O3-Bi2WO6 Nanocomposite Ornated with meso-Tetraphenylporphyrin: Interfacial Electrochemistry and Photoresponsive Detection of Nanomolar Hexavalent Cr.

Hexavalent chromium exposure via inhalation, ingestion, or both has been proven to adversely affect internal organs, induce toxic effects, cause allergies, and contribute to the development of cancer. It requires a substantial and challenging effort to detect several heavy metal ions conveniently, sensitively, and reliably by using materials that are easy to synthesize and have a high yield. The impact of light on the electrocatalytic oxidation/reduction process proves an environmentally friendly methodology with numerous applications in pollution control. The extensive use of photoactive materials in photoelectrochemical (PEC) sensors necessitates the development of stable and highly effective photoactive materials. Hence, the solvothermal synthesis of the organic-inorganic hybrid nanocomposite β-Bi2O3-Bi2WO6/H2TPP with varying weight percentages of meso-tetraphenylporphyrin (H2TPP) resulted in a selective electrode for electrocatalytic and photoelectrocatalytic reduction of Cr6+ on fluorine-doped tin oxide (FTO) by an adsorption-reduction mechanism. H2TPP increases the active site density and provides an effective surface area for efficient adsorption by providing both pyridinic- and pyrrolic-N atoms to β-Bi2O3-Bi2WO6/H2TPP. H2TPP could effectively adsorb Cr6+ in the β-Bi2O3-Bi2WO6/H2TPP composite system through electrostatic interaction, and the adsorbed Cr6+ ions were reduced to trivalent chromium Cr3+, resulting in promising Cr6+ sensing. The projected density of states and Bader charge calculations result in the electrostatic attraction among the N-2p orbital of H2TPP and the 3d and 4s orbitals of the Cr atom, resulting in the adsorption of the hexavalent Cr atom onto the active center of H2TPP. Moreover, the addition of H2TPP results in the development of a mesoporous surface that offers strong electrical conductivity, a substantial surface area, improved charge-mass transport, intimate contact between the electrolyte and catalyst, an extended fluorescence lifetime, and increased stability. The role of pH values was thoroughly investigated. All electrochemical and photoelectrochemical studies were carried out on 5 wt % H2TPP-ornated β-Bi2O3-Bi2WO6. Nanocomposite β-Bi2O3-Bi2WO6/5 wt % H2TPP demonstrated reliable cyclic stability, reproducibility, good sensitivity (8.005 μA mM cm-2), and a low limit of detection (LOD) (8.0 nM) toward photoelectrocatalytic reduction of Cr6+. The interference study in the presence of a few inorganic entities exhibited excellent selectivity. This tale amplification approach for developing a β-Bi2O3-Bi2WO6/5 wt % H2TPP nanocomposite system suggests a deeper understanding of the application of photoelectrocatalytic reduction of Cr6+ in environmental remediation with real samples under light irradiation.

An enhanced photo(electro)catalytic CO2 reduction onto advanced BiOX (X = Cl, Br, I) semiconductors and the BiOI–PdCu composite

The photoelectrocatalytic reduction of CO2 (CO2RR) onto bismuth oxyhalides (BiOX, X = Cl, Br, I) was studied through physicochemical and photoelectrochemical measurements. The successful synthesis of the BiOX compounds was carried out through a solvothermal methodology and confirmed by XRD measurements. The morphology was analyzed by SEM; meanwhile, area and pore size were determined through BET area measurements. BiOI and BiOCl present a lower particle size (3.15 and 2.71 μm, respectively); however, the sponge-like morphology presented by BiOI results in an increase in the BET area, which can enhance the catalytic activity of this semiconductor. In addition, DRS measurements allowed us to determine bandgap values of 1.9, 2.4, and 3.6 eV for BiOI, BiOBr, and BiOCl, respectively. Such results predict better visible light harvesting for BiOI. Photoelectrochemical measurements indicated that BiOX shows p-type semiconductor behavior, being the holes the majority charge carriers, making BiOI the most active material to carry out photoelectrocatalytic CO2RR. In the second stage, three different composites, BiOI–Pd, BiOI–Cu, and BiOI–PdCu, (BiOI-M; M = Pd, Cu, PdCu), were fabricated to study the influence of active metal nanoparticles (NP's) in the BiOI CO2RR activity. XRD measurements confirmed the interaction between BiOI and the metallic NP's, the three composites overpassed by 20% the BET area of pristine BiOI. Photoelectrochemical measurements indicate that all BiOI-metal composites are suitable materials to perform CO2 reduction in neutral media efficiently; however, the BiOI–PdCu composites surpassed the faradaic current of BiOI–Pd and BiOI–Cu at 0.85 V vs. RHE (3.15, 2.06 and 2.15 mA cm−2, respectively). BiOI–PdCu presented photoactivity to carry out the CO2 reduction evolving formic acid and acetic acid as the main products under visible-light irradiation.

Plasmonic titanium nitride based ammonia synthesis by Photo-electrocatalytic reduction of nitrogen

Plasmonic titanium nitride based ammonia synthesis by Photo-electrocatalytic reduction of nitrogen

NiO & CuO nanocomposites coated photoanode for conversion of CO2 into solar fuel using photoelectrochemical cell

ABSTRACT Photoelectrocatalytic reduction of carbon dioxide to solar fuel exists as a novel approach for addressing energy demand, and environmental concerns due to high efficiency and less energy requirement as compared to other technology. The predominant goal of the current work is to investigate the impact of metal oxide (NiO & CuO) supported photoanodes for enhancing CO2 conversion into solar fuel using a photoelectrochemical cell (PEC). The photoanodes were incorporated with rGO with combinations of metal oxide nanocomposites and coated on the electrode surface. The PEC consists of anode and cathode compartments divided by proton exchange membrane, the anode and cathode are filled with 0.1 M KOH and 0.5 M KCl respectively. The xenon arc lamp (100W) is used as a light source and carbon dioxide is supplied with a flow rate of 10 mL/min. The synthesized nanoparticles were characterized using XRD, FTIR, and Cyclic Voltammetry. The experimental results showed that the NiO-coated photoanode observed the better performance than CuO coated electrode and it had achieved the maximum solar fuel (Formic Acid) production rate of 9.223 μmol/hr/cm2 with a Faradic efficiency of 14.83% as compared to the control electrode.

Ameliorating the carrier dynamics behavior via plasmonic Ag-modified CuBi2O4 inverse opal for the efficient photoelectrocatalytic reduction of CO2 to CO

Low light absorption efficiency and short carrier diffusion length mainly restrict the use of CuBi2O4 as a photocathode for an efficient photoelectrocatalytic CO2 reduction reaction (PEC-CO2 RR). These inadequacies are alleviated by fabricating CuBi2O4 inverse opal photocathode modify with plasmonic Ag nanoparticles (CuBi2O4 IOs-Ag) by using a sacrificing template method. The CuBi2O4 IOs-Ag photocathode exhibits superior PEC-CO2 RR-to-CO performance with a Faraday efficiency (FE) of 92% at 0.2 V versus reversible hydrogen electrode, and this value is roughly 1.6 times that of the pristine CuBi2O4 thin film. Detail characterization and experiments reveal that the exceptional three-dimensional (3D) order structure simultaneously accelerates the mass transfer rates and enhances the light-harvesting efficiency. In addition, the introduction of Ag nanoparticles remarkably improves the surface charge distribution by forming an ohmic contact with CuBi2O4. Consequently, carrier recombination is efficiently inhibited, and the carrier dynamics behavior is improved. This work provides important insights into the design of high-performance photoelectrocatalytic systems for CO2 reduction by engineering the microstructure of catalysts with localized surface plasmon resonance effect.

0D/1D CuFeO2/CuO nanowire heterojunction arrays for improved photoelectrocatalytic reduction of CO2 to ethanol

CuO material with a bandgap of 1.2–1.9 eV and suitable energy level is a promissing material for photoelectrocatalytic reduction of CO2. However, the serious photocorrosion limits its performance improvement. Herein, an in-situ synthesis route is designed to fabricate 0D/1D CuFeO2/CuO nanowire heterojunction arrays with large specific surface. The nanowire heterojunction arrays presented excellent activity for photoelectrochemical reduction of CO2 to ethanol with an optimal faradaic efficiency of 66.73% at - 0.6 V (vs. Ag/AgCl). A heterojunction is formed between CuFeO2 and CuO, and the enhanced charge transfer mechanism is proposed based on the measurement of energy band structures. Under the action of interfacial built-in electric field of heterojunction, photogenerated holes are transferred from the valence band of CuO to CuFeO2, and photogenerated electrons are transferred from the conduction band of CuFeO2 to CuO with high selective reduction of CO2 to ethanol.