Significantly Raised Visible-Light Photocatalytic H2 Evolution on a 2D/2D ReS2 /In2 ZnS4 van der Waals Heterostructure.

Owing to dwindling fossil fuels reserves, the development of alternative renewable energy sources is globally important. Photocatalytic hydrogen (H2 ) evolution represents a practical and affordable alternative to convert sunlight into carbon-free H2 fuel. Recently, 2D/2D van der Waals heterostructures (vdWHs) have attracted significant research attention for photocatalysis. Here, for the first time a ReS2 /In2 ZnS4 2D/2D vdWH synthesized via a facile physical mixing is reported. It exhibits a highly promoted photocatalytic H2 -evolution rate of 2515 µmol h-1 g-1 . Importantly, this exceeds that for pristine In2 ZnS4 by about 22.66 times. This, therefore, makes ReS2 /In2 ZnS4 one of the most efficient In2 ZnS4 -based photocatalysts without noble-metal cocatalysts. Advanced characterizations and theoretical computations results show that interlayer electronic interaction within ReS2 /In2 ZnS4 vdWH and atomic-level S active centers along the edges of ReS2 NSs work collaboratively to result in the boosted light-induced H2 evolution. Results will be of immediate benefit in the rational design and preparation of vdWHs for applications in catalysis/(opto)electronics.

Energy Platform for Directed Charge Transfer in the Cascade Z-Scheme Heterojunction: CO2 Photoreduction without a Cocatalyst.

A universal strategy is developed to construct a cascade Z-Scheme system, in which an effective energy platform is the core to direct charge transfer and separation, blocking the unexpected type-II charge transfer pathway. The dimension-matched (001)TiO2 -g-C3 N4 /BiVO4 nanosheet heterojunction (T-CN/BVNS) is the first such model. The optimized cascade Z-Scheme exhibits ≈19-fold photoactivity improvement for CO2 reduction to CO in the absence of cocatalysts and costly sacrificial agents under visible-light irradiation, compared with BVNS, which is also superior to other reported Z-Scheme systems even with noble metals as mediators. The experimental results and DFT calculations based on van der Waals structural models on the ultrafast timescale reveal that the introduced T as the platform prolongs the lifetimes of spatially separated electrons and holes and does not compromise their reduction and oxidation potentials.

Actinyl-Modified g-C3N4 as CO2 Activation Materials for Chemical Conversion and Environmental Remedy via an Artificial Photosynthetic Route.

With the reported CO2 activation for the oxidation of benzene to phenol (-ENE → -OL) by the graphitic carbon nitride g-C3N4 (CN) via an artificial photosynthetic route as inspiration, high-valent actinyls (AnmO2)n+ (An = U, Np, Pu; m = VI, V; n = 2, 1) have been introduced for its further modification. Our calculations indicate thermodynamic spontaneity in the feasibility of g-C3N4-(AnmO2)n+ (CN-Anm) formation. The magnificent structural and electronic properties of CN-Anm are utilized for CO2 activation in terms of the rarely studied -ENE → -OL conversion. The calculated free energies show that most steps of the catalytic cycle are favored by CN-Anm complexes. The first step (carbamate formation) is slightly endothermic in all cases, where CN-U is 0.51 eV higher than CN and CN-Pu is -0.01 eV lower. All benzene addition reactions release energy, with that for CN-U being the lowest. The phenolate formation is favored by some actinyl complexes over CN, and CN-U is only 0.23 eV higher. The phenol release (resulting in formamide complexes) and CO desorption are exothermic for all CN-Anm. The overall process suggests the improved catalytic performance of actinyl-modified CN materials, and the slightly depleted uranyl-carbon nitride could be one of the promising catalysts.

Atomically Dispersed Single Co Sites in Zeolitic Imidazole Frameworks Promoting High-Efficiency Visible-Light-Driven Hydrogen Production.

As photocatalysis technology could transform renewable and clean solar energy into green hydrogen (H2 ) energy through solar water splitting, it is regarded as the "Holy Grail" in chemistry field in the 21st century. Unfortunately, the bottleneck of this technique still lies in the exploration of highly active, cost-effective, and robust photocatalysts. This work reports the design and synthesis of a novel zeolitic imidazole framework (ZIF) coupled Zn0.8 Cd0.2 S hetero-structured photocatalyst for high-performance visible-light-induced H2 production. State-of-the-art characterizations and theoretical computations disclose that the interfacial electronic interaction between ZIF and Zn0.8 Cd0.2 S, the high distribution of Zn0.8 Cd0.2 S on ZIF, and the atomically dispersed coordinately unsaturated Co sites in ZIF synergistically arouse the significantly improved visible-light photocatalytic H2 production performance.

Dimension-Matched Zinc Phthalocyanine/BiVO4 Ultrathin Nanocomposites for CO2 Reduction as Efficient Wide-Visible-Light-Driven Photocatalysts via a Cascade Charge Transfer.

Cascade charge transfer was realized by a H-bond linked zinc phthalocyanine/BiVO4 nanosheet (ZnPc/BVNS) composite, which subsequently works as an efficient wide-visible-light-driven photocatalyst for converting CO2 into CO and CH4 , as shown by product analysis and 13 C isotopic measurement. The optimized ZnPc/BVNS nanocomposite exhibits a ca. 16-fold enhancement in the quantum efficiency compared with the reported BiVO4 nanoparticles at the excitation of 520 nm with an assistance of 660 nm photons. Experimental and theoretical results show the exceptional activities are attributed to the rapid charge separation by a cascade Z-scheme charge transfer mechanism formed by the dimension-matched ultrathin (ca. 8 nm) heterojunction nanostructure. The central Zn2+ in ZnPc could accept the excited electrons from the ligand and then provide a catalytic function for CO2 reduction. This Z-scheme is also feasible for other MPc, such as FePc and CoPc, together with BVNS.

Exceptional Visible-Light Activities of TiO2-Coupled N-Doped Porous Perovskite LaFeO3 for 2,4-Dichlorophenol Decomposition and CO2 Conversion.

In this work, TiO2-coupled N-doped porous perovskite-type LaFeO3 nanocomposites as highly efficient, cheap, stable, and visible-light photocatalysts have successfully been prepared via wet chemical processes. It is shown that the amount-optimized nanocomposite exhibits exceptional visible-light photocatalytic activities for 2,4-dichlorophenol (2,4-DCP) degradation by ∼3-time enhancement and for CO2 conversion to fuels by ∼4-time enhancement, compared to the resulting porous LaFeO3 with rather high photoactivity due to its large surface area. It is clearly demonstrated, by means of various experimental data, especially for the ·OH amount evaluation, that the obviously enhanced photoactivities are attributed to the increased specific surface area by introducing pores, to the extended visible-light absorption by doping N to create surface states, and to the promoted charge transfer and separation by coupling TiO2. Moreover, it is confirmed from radical trapping experiments that the photogenerated holes are the predominant oxidants in the photocatalytic degradation of 2,4-DCP. Furthermore, a possible photocatalytic degradation mechanism for 2,4-DCP is proposed mainly based on the resultant crucial intermediate, 2-chlorosuccinic acid with m/z = 153, that readily transform into CO2 and H2O. This work opens up a new feasible route to synthesize visible-light-responsive high-activity perovskite-type nanophotocatalysts for efficient environmental remediation and energy production.

Enhanced photocatalytic activity of Cl-residual rutile TiO2 nanorods after targeted co-modification with phosphoric and boric acids.

The promotion of O2 adsorption on semiconductor surfaces for effectively capturing photogenerated electrons in the photocatalytic degradation of pollutants is highly desired. In this study, the targeted co-modification of residual chlorine rutile TiO2 nanorods with phosphoric and boric acids has been accomplished for the first time by simple wet chemical processes. The key to targeted co-modification is to connect -P-OH and -B-OH to the Cl-residual TiO2 surfaces by -Ti-OH and -Ti-Cl, respectively, consequently forming -Ti-O-P-OH and -Ti-Cl:B-OH ends. By means of the atmosphere-controlled surface photovoltage spectroscopy, the degrees for capturing photogenerated electrons by the adsorbed O2 as receptors on the resulting TiO2 nanorods are quantitatively analyzed. It is confirmed that the targeted co-modification could greatly promote the capture of the photogenerated electrons compared to the phosphate and borate modification alone. This is attributed to increased amounts of adsorbed O2 based on electrochemical O2 reduction and O2 temperature-programmed desorption measurements, further leading to the enhanced separation of photogenerated charges, characterized by an increase in the amount of produced hydroxyl radicals. This is responsible for the obviously enhanced photocatalytic activity of TiO2 nanorods towards the degradation of colorless gas-phase acetaldehyde and liquid-phase phenol. This work would provide us a feasible route for the co-modification with inorganic acids to synthesize efficient nanosized TiO2-based photocatalysts.

Improved photoactivity of TiO2-Fe2O3 nanocomposites for visible-light water splitting after phosphate bridging and its mechanism.

In this work, we have successfully constructed phosphate bridges in a TiO2-Fe2O3 nanocomposite using wet-chemical processes. Based on FTIR, XPS and TEM measurements it is confirmed that phosphate groups form bridges that effectively connect TiO2 and α-Fe2O3. From steady-state surface photovoltage spectra (SS-SPS) and transient-state surface photovoltage (TS-SPV) measurements in N2, it is clearly demonstrated that the separation and lifetime of the photogenerated charge carriers in the TiO2-Fe2O3 nanocomposite are greatly enhanced by the introduction of the phosphate bridges. As a consequence, the visible light photocatalytic activity in water reduction by methanol and the photoelectrochemical water oxidation were obviously improved after phosphate bridging. It is concluded mainly on the basis of ultra-low-temperature EPR signals, EIS spectra, and the normalized photocurrent action spectra that the photogenerated electrons of α-Fe2O3 under irradiation with visible light would transfer to TiO2 in the nanocomposite, and the built phosphate bridges are favorable for charge transportation, leading to the greatly-increased separation and lifetime of visible-light excited charge carriers. This work provides a feasible route to improve the photoactivity of other visible-response nanocomposites for water splitting.

Surface tuning for oxide-based nanomaterials as efficient photocatalysts.

Due to the increasingly polluted environment and the gradual depletion of fossil fuel reserves, the development of renewable technologies for environmental remediation and energy production is highly desirable. Over the past decades, oxide-based semiconductor photocatalysis has attracted much attention. On various frontiers for efficient photocatalysis, surface-tuning strategies for synthesis and modification of oxides on the nanometer scale have progressed at a fast pace. Hence, it is of significance to review recent advances in the development of surface tuning for oxide-based nanomaterials as activity-enhanced photocatalysts. In this review, special emphases, especially for recent advances in our group, are given to surface tuning of novel nanocrystallites for high thermal stability, hierarchical structure assembly, heterojunctional nanocomposites and high-energy-facet exposure, along with effective testing tools for photogenerated charge properties at the surfaces and/or interfaces. This is of great significance for fields related to energy and environment from scientific and engineering viewpoints.

Synergistic effect of atomically dispersed Cu species and Ti-defects for boosting photocatalytic CO2 reduction over hierarchical TiO2.

The photocatalytic water-mediated CO2 reduction reaction, which holds great promise for the conversion of CO2 into valuable chemicals, is often hindered by inefficient separation of photogenerated charges and a lack of suitable catalytic sites. Herein, we have developed a glycerol coordination assembly approach to precisely control the distribution of atomically dispersed Cu species by occupying Ti-defects and adjusting the ratio between Cu species and Ti-defects in a hierarchical TiO2. The optimal sample demonstrates a ∼4-fold improvement in CO2-to-CO conversion compared to normal TiO2 nanoparticles. The high activity could be attributed to the Ti defects, which enhance the photogenerated charge separation and simultaneously facilitate the adsorption of water molecules, thereby promoting the water oxidation reaction. Moreover, by means of in situ EPR and FTIR spectra, we have demonstrated that Cu species can effectively capture photogenerated electrons and facilitate the adsorption of CO2, so as to catalyze the reduction of CO2. This work provides a strategy for the construction of atomic-level synergistic catalytic sites and the utilization of in situ techniques to reveal the underlying mechanism.

Construction of a CoNiHHTP MOF/PHI Z-Scheme Heterojunction for ppb Level NO2 Photoelectric Sensing with 405 nm Irradiation at RT.

Ultrasensitive photoelectric detection of nitrogen dioxide (NO2) with PHI under visible light irradiation at room temperature (RT) remains an ongoing challenge due to the low charge separation and scarce adsorption sites. In this work, a dimensionally matched ultrathin CoNiHHTP MOF/PHI Z-scheme heterojunction is successfully constructed by taking advantage of the π-π interactions existing between the CoNiHHTP MOF and PHI. The amount-optimized heterojunction possesses a record detection limit of 1 ppb (response = 15.6%) for NO2 under 405 nm irradiation at RT, with reduced responsive (3.6 min) and recovery (2.7 min) times, good selectivity and reversibility, and long-time stability (150 days) compared with PHI, even superior to others reported at RT. Based on the time-resolved photoluminescence spectra, in situ X-ray photoelectron spectra, and diffuse reflectance infrared Fourier transform spectroscopy results, the resulting sensing performance is attributed to the favorable Z-scheme charge transfer and separation. Moreover, the Ni nodes favorably present in adjacent metal sites between the lamellae contribute to charge transfer and redistribution, whereas Co nodes could act as selective centers for promoted adsorption of NO2. Interestingly, it is confirmed that the CoNiHHTP MOF/PHI heterojunction could effectively reduce the influence of O2 in the gas-sensitive reaction due to their unique bimetallic (Co and Ni) nodes, which is also favorable for the improved sensing performances for NO2. This work provides a feasible strategy to develop promising PHI-based optoelectronic gas sensors at RT.

Visual Eosin Y-Based Photosensitization Sensing Systems for Ultrasensitive Detection of Diclofenac with Single-Atom Co─N2O2 Site-Immobilized g-C3N4 Nanosheets.

It is highly desired to develop a visual sensing system for ultrasensitive detection of colorless diclofenac (DCF), yet with a significant challenge. Herein, a novel dye-based photosensitization sensing system has been successfully developed for detecting DCF for the first time, in which the used dye eosin Y (DeY) can strongly absorb visible light and then be decolorized obviously by transferring photogenerated electrons to g-C3N4 nanosheets (CN), while the built single-atomic Co─N2O2 sites on CN by boron-oxygen connection can competitively adsorb DCF to impede the photosensitization decoloration of DeY. This system exhibits a broad detection range from 8 ng L-1 to 2 mg L-1 with 535 nm light, an exceptionally low detection limit (3.5 ng L-1), and remarkable selectivity. Through the time-resolved, in situ technologies, and theoretical calculations, the decolorization of DeY is attributed to the disruption of DeY's conjugated structure caused by the triplet excited state electron transfer from DeY to CN, meanwhile, the adsorbed oxygen facilitates the charge transfer process. The preferential adsorption of DCF mainly depends on the strong interactions between the as-constructed single-atom Co and Cl in DCF. This study opens an innovative light-driven sensing system by combining dye and single-atom metal/nanomaterial for visually intuitive detection of environmental pollutants.

Improved Performance of g-C3N4 for Optoelectronic Detection of NO2 Gas by Coupling Metal-Organic Framework Nanosheets with Coordinatively Unsaturated Ni(II) Sites.

Sensitive and selective optoelectronic detection of NO2 with g-C3N4 (CN) is critical, but it remains challenging to achieve ultralow concentration (ppb-level) detection. Herein, Ni metal-organic frameworks/CN nanosheet heterojunctions were successfully fabricated by the electrostatic induced assembly strategy and then treated by a post-alkali etching process for creating coordinatively unsaturated Ni(II) sites. The optimized heterojunction exhibits a record detection limitation of 1 ppb for NO2, well below that observed on pristine CN, and an outstanding selectivity over other gases, along with long-time stability (120 days) at room temperature. The resulting superior detection performance benefits from the enhanced charge transfer and separation of the closely contacted heterojunction interface and the favorable adsorption of NO2 by unsaturated Ni(II) as selective adsorption sites mainly by means of the time-resolved photoluminescence spectra and in situ X-ray photoelectron spectra. Moreover, the in situ Fourier transform infrared spectra and temperature-programmed desorption disclose that the promotion adsorption of NO2 depends on the strengthened interaction between NO2 and Ni(II) node sites at the aid of OH groups from unsaturated coordination. This work offers a versatile solution to develop promising CN-based optoelectronic sensors at room temperature.

Photocatalytic production of ethylene and propionic acid from plastic waste by titania-supported atomically dispersed Pd species.

Current chemical recycling of bulk synthetic plastic, polyethylene (PE), operates at high temperature/pressure and yields a complex mixture of products. PE conversion under mild conditions and with good selectivity toward value-added chemicals remains a practical challenge. Here, we demonstrate an atomic engineering strategy to modify a TiO2 photocatalyst with reversible Pd species for the selective conversion of PE to ethylene (C2H4) and propionic acid via dicarboxylic acid intermediates under moderate conditions. TiO2-supported atomically dispersed Pd species exhibits C2H4 evolution of 531.2 µmol gcat-1 hour-1, 408 times that of pristine TiO2. The liquid product is a valuable chemical propanoic acid with 98.8% selectivity. Plastic conversion with a C2 hydrocarbon yield of 0.9% and a propionic acid yield of 6.3% was achieved in oxidation coupled with 3 hours of photoreaction. In situ spectroscopic studies confirm a dual role of atomic Pd species: an electron acceptor to boost charge separation/transfer for efficient photoredox, and a mediator to stabilize reaction intermediates for selective decarboxylation.

Controlled Synthesis of Nitro-Terminated Oligothiophene/Crystallinity-Improved g-C3N4 Heterojunctions for Enhanced Visible-Light Catalytic H2 Production.

It is highly desired to explore closely contacted polymer semiconductor/g-C3N4 heterojunction photocatalysts with promoted photogenerated-carrier separation and extended visible-light response for efficient visible-light-driven H2 production. Here, we first synthesized the nitro-terminated oligothiophene (OTh) by the controlled copolymerization of thiophene and 2-nitrothiophene monomers, then constructed the nitro-terminated oligothiophene/crystallinity-improved g-C3N4 (OTh/g-C3N4) heterojunctions by a grinding-induced combination strategy. The ratio-optimized 20OTh5/g-C3N4 shows highly efficient H2 production activity up to 3.63 mmol h-1 g-1 under visible-light irradiation, with ∼25.9-time enhancement compared to that of g-C3N4. As verified by time-resolved photoluminescence spectra, surface photovoltage spectra, and the fluorescence spectra related to •OH amounts, the improved photocatalytic activity is due to the promoted photogenerated-carrier transfer and separation in the heterojunctions and the expanded visible-light response. It is also confirmed that the controlled OTh chain length, improved g-C3N4 crystallinity, and tight interface contact dependent on the hydrogen bonds and N···S interactions between OTh and g-C3N4 are reasonable for enhanced photogenerated-carrier separation with the electron transfer from OTh to g-C3N4. This work illustrates a feasible strategy to construct efficient polymer semiconductor/g-C3N4 heterojunction photocatalysts for solar-light-driven H2 production.

Atomically Dispersed ZnN5 Sites Immobilized on g-C3 N4 Nanosheets for Ultrasensitive Selective Detection of Phenanthrene by Dual Ratiometric Fluorescence.

Ultrasensitively selective detection of trace polycyclic aromatic hydrocarbons (PAHs) like phenanthrene (PHE) is critical but remains challenging. Herein, atomically dispersed Zn sites on g-C3 N4 nanosheets (sZn-CN) are constructed by thermal polymerization of a Zn-cyanuric acid-melamine supramolecular precursor for the fluorescence detection of PHE. A high amount (1.6 wt%) of sZn is grafted in the cave of CN with one N vacancy in the form of unique Zn(II)N5 coordination. The optimized sZn-CN achieves a wide detection range (1 ng L-1 to 5 mg L-1 ), ultralow detection limit (0.35 ng L-1 , with 5-order magnitude improvement over CN), and ultrahigh selectivity toward PHE even among typical PAHs based on the built PHE-CN dual ratiometric fluorescence method. By means of in situ Fourier transform infrared spectroscopy, time-resolved absorption and fluorescence spectroscopy, and theoretical calculations, the resulting superior detection performance is attributed to the favorable selective adsorption of PHE on as-constructed atomic Zn(II)N5 sites via the ionic cation-π interactions (Znδ+ C2 δ- type), and the fluorescence quenching is dominated by the inner filter effect (IFE) from the multilayer adsorption of PHE at low concentrations, while it is done by the protruded photogenerated electron-transfer process, as well as IFE from the monolayer adsorption of PHE at ultralow concentration.

Improving CO2 photoconversion with ionic liquid and Co single atoms.

Photocatalytic CO2 conversion promises an ideal route to store solar energy into chemical bonds. However, sluggish electron kinetics and unfavorable product selectivity remain unresolved challenges. Here, an ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate, and borate-anchored Co single atoms were separately loaded on ultrathin g-C3N4 nanosheets. The optimized nanocomposite photocatalyst produces CO and CH4 from CO2 and water under UV-vis light irradiation, exhibiting a 42-fold photoactivity enhancement compared with g-C3N4 and nearly 100% selectivity towards CO2 reduction. Experimental and theoretical results reveal that the ionic liquid extracts electrons and facilitates CO2 reduction, whereas Co single atoms trap holes and catalyze water oxidation. More importantly, the maximum electron transfer efficiency for CO2 photoreduction, as measured with in-situ µs-transient absorption spectroscopy, is found to be 35.3%, owing to the combined effect of the ionic liquid and Co single atoms. This work offers a feasible strategy for efficiently converting CO2 to valuable chemicals.

Atomic-Level Regulated 2D ReSe2 : A Universal Platform Boostin Photocatalysis.

Solar hydrogen (H2 ) generation via photocatalytic water splitting is practically promising, environmentally benign, and sustainably carbon neutral. It is important therefore to understand how to controllably engineer photocatalysts at the atomic level. In this work, atomic-level engineering of defected ReSe2 nanosheets (NSs) is reported to significantly boost photocatalytic H2 evolution on various semiconductor photocatalysts including TiO2 , CdS, ZnIn2 S4 , and C3 N4 . Advanced characterizations, such as atomic-resolution aberration-corrected scanning transmission electron microscopy (AC-STEM), synchrotron-based X-ray absorption near edge structure (XANES), in situ X-ray photoelectron spectroscopy (XPS), transient-state surface photovoltage (SPV) spectroscopy, and transient-state photoluminescence (PL) spectroscopy, together with theoretical computations confirm that the strongly coupled ReSe2 /TiO2 interface and substantial atomic-level active sites of defected ReSe2 NSs result in the significantly raised activity of ReSe2 /TiO2 . This work not only for the first time realizes the atomic-level engineering of ReSe2 NSs as a versatile platform to significantly raise the activities on different photocatalysts, but, more importantly, underscores the immense importance of atomic-level synthesis and exploration on 2D materials for energy conversion and storage.

Improved Visible-Light Photocatalytic H2 Evolution of G-C3N4 Nanosheets by Constructing Heterojunctions with Nano-Sized Poly(3-Thiophenecarboxylic Acid) and Coordinating Fe(III).

It is highly desirable to enhance the photogenerated charge separation of g-C3N4 by constructing efficient heterojunctions, especially with an additional organic constitution for solar-hydrogen conversion. Herein, g-C3N4 nanosheets have been modified controllably with nano-sized poly(3-thiophenecarboxylic acid) (PTA) through in situ photopolymerization and then coordinated with Fe(III) via the -COOH groups of modified PTA, forming an interface of tightly contacted nanoheterojunctions between the Fe(III)-coordinated PTA and g-C3N4. The resulting ratio-optimized nanoheterojunction displays a ~4.6-fold enhancement of the visible-light photocatalytic H2 evolution activity compared to bare g-C3N4. Based on the surface photovoltage spectra, measurements of the amount of •OH produced, photoluminescence (PL) spectra, photoelectrochemical curves, and single-wavelength photocurrent action spectra, it was confirmed that the improved photoactivity of g-C3N4 is attributed to the significantly promoted charge separation by the transfer of high-energy electrons from the lowest unoccupied molecular orbital (LUMO) of g-C3N4 to the modified PTA via the formed tight interface, dependent on the hydrogen bond interaction between the -COOH of PTA and the -NH2 of g-C3N4, and the continuous transfer to the coordinated Fe(III) with -OH favorable for connection with Pt as the cocatalyst. This study demonstrates a feasible strategy for solar-light-driven energy production over the large family of g-C3N4 heterojunction photocatalysts with exceptional visible-light activities.

A Z-Scheme Heterojunctional Photocatalyst Engineered with Spatially Separated Dual Redox Sites for Selective CO2 Reduction with Water: Insight by In Situ µs-Transient Absorption Spectra.

Solar-driven CO2 reduction by water with a Z-scheme heterojunction affords an avenue to access energy storage and to alleviate greenhouse gas (GHG) emissions, yet the separation of charge carriers and the integrative regulation of water oxidation and CO2 activation sites remain challenging. Here, a BiVO4 /g-C3 N4 (BVO/CN) Z-scheme heterojunction as such a prototype is constructed by spatially separated dual sites with CoOx clusters and imidazolium ionic liquids (IL) toward CO2 photoreduction. The optimized CoOx -BVO/CN-IL delivers an ≈80-fold CO production rate without H2 evolution compared with urea-C3 N4 counterpart, together with nearly stoichiometric O2 gas produced. Experimental results and DFT calculations unveil the cascade Z-scheme charge transfer and subsequently the prominent redox co-catalysis by CoOx and IL for holes-H2 O oxidation and electrons-CO2 reduction, respectively. Moreover, in situ µs-transient absorption spectra clearly show the function of each cocatalyst and quantitatively reveal that the resulting CoOx -BVO/CN-IL reaches up to the electron transfer efficiency of 36.4% for CO2 reduction, far beyond those for BVO/CN (4.0%) and urea-CN (0.8%), underlining an exceptional synergy of dual reaction sites engineering. This work provides deep insights and guidelines for the rational design of highly efficient Z-scheme heterojunctions with precise redox catalytic sites toward solar fuel production.