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A novel bimetallic CoMoB-coupled carbon nitride with dual moiety defects (CN-TH 3/3) Schottky junction photocatalyst (CoMoB/CN-TH 3/3) was designed for photocatalytic nitrogen fixation. [Display omitted] • A novel CoMoB/(CN-TH 3/3) Schottky junction photocatalyst was designed for photocatalytic NRR. • Both of the intralayer exciton characteristics and the visible light adsorption capacity were altered. • The synergistic effect of CoMoB and CN-TH 3/3 accelerated charge transfer and enhanced the N 2 adsorption and activation. • The photocatalytic NRR performance of optimum CoMoB/CN-TH 3/3 is 6.2 times higher than CN. The sustainable generation of ammonia by photocatalytic nitrogen fixation under mild conditions is fascinating compared to conventional industrial processes. Nevertheless, owing to the low charge transfer efficiency, the insufficient light absorption capacity and limited active sites of the photocatalyst cause the difficult adsorption and activation of N 2 molecules, thereby resulting in a low photocatalytic conversion efficiency. Herein, a novel bimetallic CoMoB nanosheets (CoMoB) co-catalyst modified carbon nitride with dual moiety defects (CN-TH 3/3) Schottky junction photocatalyst is designed for photocatalytic nitrogen reduction reaction (NRR). The photocatalytic nitrogen reduction rate of the optimized CoMoB/CN-TH 3/3 photocatalyst is 4.81 mM·g−1·h−1, which is 6.2 and 2.2 times higher than carbon nitride (CN) (0.78 mM·g−1·h−1) and CN-TH 3/3 (2.21 mM·g−1·h−1), respectively. The excellent photocatalytic NRR performance is ascribed not only to the introduction of dual moiety defects (cyano and cyanamide groups) that extends the visible light absorption range and promotes exciton polarization dissociation, but also to the formation of interfacial electric field between CoMoB and CN-TH 3/3 , which effectively facilitates the interfacial charge transfer. Thus, the synergistic interaction between CN-TH 3/3 and CoMoB further increases the electron numble of CoMoB active sites, which effectively strengthens the adsorption and activation of N 2 and weakens the N N triple bond, thereby enhancing the photocatalytic NRR activity. This work highlights the introduced dual moiety defects and bimetallic CoMoB co-catalyst to synergistically enhance the photocatalytic nitrogen reduction performance. [ABSTRACT FROM AUTHOR]

Unraveling how mid-gap state energy level of graphitic carbon nitride (g-C 3 N 4) promote near-infrared (NIR) driven photochemical energy conversion at the molecular level remains a grand challenge. Here, we report a series of S double-site-doped ultrathin g-C 3 N 4 nanosheets (SUCN) with adjustable intermediate band gap benefits from light response over NIR region. The SUCN produced after optimizing S double-site doping can effectively generate hydrogen (H 2) under NIR-light irradiation. The highest H 2 generation rate achieved was respectively 9.35 and 17.46 μmol g−1 h−1 under λ = 765 and λ > 800 nm, which is firstly expended photocatalytic activity of S-doped g-C 3 N 4 to NIR region beyond λ > 765 nm. We proposed a molecular-level method, i.e., the localized oxidation state of proton acceptor triethanolamine (TEOA) in the mid-gap state to ensure the NIR-driven H 2 generating behavior. [Display omitted] • g-C 3 N 4 was doped with S atoms at a specific site of the triazine skeleton. • S doping provides an adjustable intermediate band gap of g-C 3 N 4. • The 0.36-SUCN obtained 43 times higher PHE than g-C 3 N 4. • The S-doped g-C 3 N 4 firstly realized PHE in the near-infrared region. • The NIR-driven H 2 generation was firstly demonstrated by a molecular-level method. [ABSTRACT FROM AUTHOR]

The MIL-53Fe@g-C 3 N 4 samples were prepared by solvothermal method and recorded as CM-x. The potocatalytic activity of the MIL-53Fe@g-C 3 N 4 was significantly higher than MIL-53Fe, and it might be due to the successfully constructed heterojunction promoting the migration and separation effciency of photo-generated electron and hole pairs. In order to further enhance the potocatalytic activity of the MIL-53Fe@g-C 3 N 4 , peroxymonosulfate was introduced into the MIL-53Fe@g-C 3 N 4 /Vis system, and the peroxymonosulfate could be simultaneously activated by photogenerated electron and iron to form sulfate radical under visible light irradiation. Therefore, the degradation efficiency of oxytetracycline hydrochloride was enhanced obviously. Meantime, the effects of peroxymonosulfate dosage, oxytetracycline hydrochloride concentration, temperature and pH on the degradation efficiency of oxytetracycline hydrochloride were studied systematically. Meanwhile, the free radical catching experiments and electron spin resonance analysis confirmed that the main active substances were sulfate radical and hole. Finally, the mechanism and possible degradation pathways of MIL-53Fe@g-C 3 N 4 activating peroxymonosulfate to degrade oxytetracycline hydrochloride were proposed. [Display omitted] • MIL-53Fe@g-C 3 N 4 photocatalysts was synthesized by solvothermal method. • Peroxymonosulfate was activated by photogenerated e− and Fe. • The SO 4 •− and •OH mainly contributed to oxytetracycline hydrochloride degradation. [ABSTRACT FROM AUTHOR]

Two-dimensional g-C 3 N 4 /Bi 2 WO 6 heterojunction photocatalysts have been successfully synthesized by a multi-step method. Based on the structure and morphology characterization, the as-prepared photocatalysts exhibited a nanosheet/nanosheet hybrid structure, which could provide a large heterogeneous surface area, increase the transmission route of photo-induced carriers and then suppress the charge recombination. To investigate the practical photocatalytic performance for water purification of these heterojunction photocatalysts, organic dyes such as Rhodamine B (RhB) and antibiotics including tetracycline (TC) and ciprofloxacin (CIP) have been selected as the target pollution under visible-light irradiation. The optimum photocatalyst (the weight ratio of g-C 3 N 4 to Bi 2 WO 6 is 1:0.67) was more than three times and two times than pure g-C 3 N 4 and Bi 2 WO 6 , respectively. The enhanced photocatalytic activities of g-C 3 N 4 /Bi 2 WO 6 heterojunction photocatalysts might be ascribed to the two-dimensional structure. In combination of the experiment results, the possible photo-induced charge transfer route has been detailed illustrated. [ABSTRACT FROM AUTHOR]

[Display omitted] The inherent electron localized heptazine structure of carbon nitride (CN) derived from intrinsic tertiary N (N 3C) bridging structure makes the photogenerated charge separation rather difficult, which severely limits photocatalytic CO 2 activity of CN. Therefore, modulation of N 3C bridging structure of CN is highly desirable to enhance the charge separation efficiency of CN. Herein, we reported a novel thiophene-bridged CN (BTCN) with intramolecular donor-π-acceptor (D-π-A) systems synthesized by nucleophilic substitution and Schiff base reaction to improve the photogenerated charge separation efficiency. The experimental and density functional theory (DFT) results indicate that this BTCN exhibits a high π-electron delocalization range and enhanced photogenerated charge transfer efficiency, which mainly account for the enhanced photocatalytic activity. The optimal BTCN photocatalyst exhibits enhanced charge separation efficiency and higher photocatalytic CO 2 reduction activity with a CO yield of 23.02 μmol·g−1·h−1, which was higher than those of CN and edge-modified CN (ETCN) counterpart. This work highlights the importance of regulation of π-electron delocalization for the design of highly active CN photocatalysts via the rational substitution of N 3C bridging structure with π-spacer molecular linkages for photocatalytic CO 2 reduction. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Mo 2 C can be used as a cocatalyst for photocatalytic hydrogen evolution over K+Ca 2 Nb 3 O 10 − nanosheets. • The Mo 2 C/K+Ca 2 Nb 3 O 10 − heterojunction showed enhanced photocatalytic H 2 evolution activity. • The improved charge separation and transfer contributes to the enhanced catalytic activity. Developing low cost and highly efficient catalysts for photocatalytic hydrogen (H 2) evolution reaction holds significant function in water splitting. The co-catalysts load on semiconductor can promote the rapid separation and migration of photon-generated carriers, active interfacial reaction and suppress photocorrosion. Herein, we report the synthesis of Mo 2 C nanoparticles (NPs) decorated K+Ca 2 Nb 3 O 10 − nanosheets (K+CNO− NSs) heterojunction photocatalyst, where the Mo 2 C is used as a co-catalyst. The optimal Mo 2 C/K+CNO− sample with a Mo 2 C loading amount of 3 wt% yields an enhanced H 2 production rate of 686.5 μmol g‒1, which is about 8.8 times higher than that of bare K+CNO‒ NSs (78.1 μmol g‒1). The enhanced photocatalytic activity might be ascribed to the faster photoinduced electrons transfer due to the ultrathin structure of K+CNO− NSs and effective charge carrier separation derived from the abundant contact heterointerfaces between K+CNO− NSs and Mo 2 C NPs. This study provides a guidance to construct efficient non-noble metal co-catalyst for photocatalytic H 2 evolution from water splitting. [ABSTRACT FROM AUTHOR]

[Display omitted] Photo-chemical conversion of CO 2 into solar fuels by photocatalysts is a promising and sustainable strategy in response to the ever-increasing environmental problems and imminent energy crisis. However, it is unavoidably impeded by the insufficient active site, undesirable inert charge transfer and fast recombination of photogenerated charge carriers on semiconductor photocatalysts. In this work, all these challenges are overcome by construction of a novel defect-engineered Z-scheme hybrid photocatalyst, which is comprised of three-dimensional (3D) BiOBr nanoflowers assembled by nanosheets with abundant oxygen vacancies (BiOBr-V O) and two-dimensional (2D) HNb 3 O 8 nanosheets (HNb 3 O 8 NS). The special 3D-2D architecture structure is beneficial to preventing photocatalyst stacking and providing more active sites, and the introduced oxygen vacancies not only broaden the light absorption range but also enhance the electrical conductivity. More importantly, the constructed Z-scheme photocatalytic system could accelerate the charge carriers transfer and separation. As a result, the optimal BiOBr-V O /HNb 3 O 8 NS (50%-BiOBr-V O /HNb 3 O 8 NS) shows a high CO production yield of 164.6 μmol·g−1 with the selectivity achieves to 98.7% in a mild gas-solid system using water as electron donors. Moreover, the BiOBr-V O /HNb 3 O 8 NS photocatalyst keeps high photocatalytic activity after five cycles under the identical experimental conditions, demonstrating its excellent long-term durability. This work provided an original strategy to design a new hybrid structure photocatalyst involved V O s, thus guiding a new way to further enhance CO 2 reduction activity of photocatalyst. [ABSTRACT FROM AUTHOR]

In this work, a high-performance composite photocatalyst composed of WO3 nanosheets and Bi24O31Br10 nanosheets was successfully synthesized. The photocatalytic activity of the obtained samples was studied by the degradation of tetracycline hydrochloride under visible light irradiation. The results showed that Bi24O31Br10 modified with the appropriate amount of WO3 nanosheet exhibits higher catalytic activity and stability during the photocatalytic processes, and the holes (h+) is involved in the photolysis reaction as the main active species. The crystallization, morphology, optical and electrochemical properties of the as-prepared composite photocatalyst were characterized, and the mechanism of high photocatalytic activity was also explored. The optimal sample (10%-WO3/Bi24O31Br10) exhibited the best performance for tetracycline hydrochloride (TC) degradation, and more than 80% of the TC was degraded after 60 min under light irradiation. The degradation rate constant k was about 3.34-fold and 1.54-fold higher than pure WO3 and Bi24O31Br10, respectively. Its high photocatalytic performance can be attributed to the following reasons: the appropriate conduction band and valence band positions between WO3 and Bi24O31Br10, the close contact between the two visible light-driven photocatalysts, and the effective separation of the spatial charge. Our work may help to further expand the potential application of oxygen-rich bismuth oxyhalides photocatalyst in wastewater treatment, and provide a new strategy for the modification of nanostructured photocatalysts. [ABSTRACT FROM AUTHOR]

A Bi/HNb 3 O 8 -Vo hybrid photocatalyst was designed by a simple two-step method. Through the synergistic effect of oxygen vacancies and Bi nanoparticles on the catalyst surface, the electron-hole complexation rate was reduced, and the adsorption and activation of N 2 was enhanced. [Display omitted] Due to the high stability of the N 2 molecule and the low charge separation efficiency, the photocatalytic reduction of N 2 to high-value chemicals (NH 3) under mild conditions remains a great challenge. Herein, a composite photocatalyst (Bi/HNb 3 O 8 -Vo nanosheets) with Bi nanoparticles modified the HNb 3 O 8 -Vo nanosheets are designed for the conversion of N 2 into NH 3. In this design, the introduction of oxygen vacancies on the catalyst surface facilitates the formation of defective energy levels within the band gap of HNb 3 O 8 -Vo NS, which promotes the absorption of visible light, and enhances the charge carrier transport and separation. Bi nanoparticles co-catalyst not only facilitates the separation and migration of photogenerated charges, but also acts as reaction sites to adsorb and activate N 2 molecule. Consequently, the optimized 5 % Bi/HNb 3 O 8 -Vo photocatalysts show a NH 3 yield of 372.7 μmol/L g−1h−1 under full spectral irradiation without sacrificial agent, which is much higher than that of HNb 3 O 8 NS (92.2 μmol/L g−1h−1). This work provides a new way for the design of efficient N 2 reduction photocatalysts through the synergistic effect of surface vacancies and metal co-catalysts. [ABSTRACT FROM AUTHOR]

A Bi/HNb 3 O 8 -Vo hybrid photocatalyst was designed by a simple two-step method. Through the synergistic effect of oxygen vacancies and Bi nanoparticles on the catalyst surface, the electron-hole complexation rate was reduced, and the adsorption and activation of N 2 was enhanced. [Display omitted] Due to the high stability of the N 2 molecule and the low charge separation efficiency, the photocatalytic reduction of N 2 to high-value chemicals (NH 3) under mild conditions remains a great challenge. Herein, a composite photocatalyst (Bi/HNb 3 O 8 -Vo nanosheets) with Bi nanoparticles modified the HNb 3 O 8 -Vo nanosheets are designed for the conversion of N 2 into NH 3. In this design, the introduction of oxygen vacancies on the catalyst surface facilitates the formation of defective energy levels within the band gap of HNb 3 O 8 -Vo NS, which promotes the absorption of visible light, and enhances the charge carrier transport and separation. Bi nanoparticles co-catalyst not only facilitates the separation and migration of photogenerated charges, but also acts as reaction sites to adsorb and activate N 2 molecule. Consequently, the optimized 5 % Bi/HNb 3 O 8 -Vo photocatalysts show a NH 3 yield of 372.7 μmol/L g−1h−1 under full spectral irradiation without sacrificial agent, which is much higher than that of HNb 3 O 8 NS (92.2 μmol/L g−1h−1). This work provides a new way for the design of efficient N 2 reduction photocatalysts through the synergistic effect of surface vacancies and metal co-catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Z-scheme mechanism was demonstrated by ESR characterizations. • The high photocatalytic activity is owing to the successful fabrication of Z-scheme heterojunction and efficient charge separation. • Direct Z-scheme system enhances the separation of photogenerated charge carriers. • 0D/2D Zn-AgIn 5 S 8 QDs/α-Fe 2 O 3 heterostructures exhibit the efficient photocatalytic H 2 generation. Multinary sulfide quantum dots (QDs) have exhibited outstanding advantages including large surface areas, unique optical properties and adjustable band gap, which are beneficial for visible-active photocatalysis. However, the use of QDs also brings about serious issues of charge recombination and particle agglomeration. Here, a rational design of direct 0D/2D Z-scheme heterojunction of Zn-AgIn 5 S 8 /α-Fe 2 O 3 is described. Appropriate band alignment is conducive to the construction of Z-scheme heterostructures, thus enhancing the redox ability of the semiconductors and inhibiting the charge recombination. Simultaneously, the zeta potential differences between the two semiconductors can make them achieve a close interface contact by electrostatic adsorption and then the 0D Zn-AgIn 5 S 8 (ZAIS) QDs can be dispersed uniformly on 2D α-Fe 2 O 3 nanosheets, which can reduce the agglomeration of QDs. At the same time, the advantages of large specific surface area and short electron transmission path of QDs can also be exerted. Meanwhile, α-Fe 2 O 3 nanosheets with high conductivity can rapidly lead out the photogenerated charge carriers and thus suppress the recombination of the electrons and holes in QDs. The optimum nanocomposites with 3 wt% α-Fe 2 O 3 nanosheets display a photocatalytic H 2 evolution rate of 1.7 mmol g−1 h−1, 3.5 times to that of pure QDs, with an apparent quantum efficiency of 7.48% at 450 nm. Electrochemiluminescence spectra, time-resolved photoluminescence spectra and electron spin resonance spectra further testify the enhanced charge transfer and the direct Z-scheme mechanism of the 0D/2D heterojunction. This work emphasizes the suitable band matching to adjust the exciton properties and charge transfer characteristics of QDs by constructing Z-scheme heterojunction for efficient utilization of visible light. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel Au/Ar-CN photocatalyst was designed for the photocatalytic CO 2 reduction. • Intramolecular modifications regulate the local π-electron distribution of CN. • The Schottky junctions modulate space charge transfer and provide CO 2 RR sites. • Au/Ar-CN performs high photocatalytic evolution CO rate of 32.03 μmol·g–1·h–1. Polymeric carbon nitride (CN) is one of the most prospective non-metallic catalysts at present, yet its photocatalytic activity is unsatisfactory mainly due to the poor intramolecular charge carrier separation efficiency originated form its special electronic structure. Herein, we demonstrate a synergistic strategy to improve the charge carriers transfer and separation efficiency of CN synchronously by extending the π-conjugated system via incorporation of O-containing aromatic ring in the CN skeleton (Ar-CN) and constructing a Schottky junction via decoration of Au nanoparticles (Au Nps). The introduced O-containing aromatic ring can create a local asymmetry, delocalize the π-conjugated system of CN, and thus promote the in-plane charge transport of CN, while the formed loading of Au Nps can further promote interlayer charge transfer efficiency of Ar-CN. The optimized 3 %Au/Ar-CN photocatalyst exhibits a high photocatalytic CO 2 activity with a CO yield of 32.03 μmol·g−1·h−1, which is higher than those of CN (2.38 μmol·g−1·h−1) and Ar-CN (6.42 μmol·g−1·h−1). This study provides a feasible co-modification strategy to enhance the charge transfer and photocatalytic activity of CN by extending the π-conjugation system and constructing Schottky junctions. [ABSTRACT FROM AUTHOR]

The artificially Z-scheme heterojunctions between WO 3 nanosheet and SnNb 2 O 6 nanosheet with strongly coupled heterointerfaces were successfully constructed via a simple hydrothermal coassembly method. Transmission electron microscopy (TEM) and high-resolution TEM proved that an intimate contact interface was formed. The synthesized heterojunctions exhibites enhanced photodegradation efficiency for Rhodamine B under irradiation of visible light, and the highest reaction rate over 30%-WO 3 /SnNb 2 O 6 nanosheet heterojunctions is about 4.7-fold and 2-fold higher than that of pristine WO 3 and SnNb 2 O 6 , respectively. Such a considerable improvement could be mainly attributed to the rapid migration of the photo-induced e − /h + pairs through the nanosheets-coupled heterojunction interfaces. A possible directly Z-scheme charge transfer mechanism was proposed for the elimination of organic contaminants under irradiation of visible light. This work may furnish new insights into development of novel 2D/2D nanosheet heterojunctions with the enhanced photocatalytic activity. [ABSTRACT FROM AUTHOR]

Water-soluble deoxynivalenol (DON) pose a major threat as a potential organic pollutant to water environmental quality. DON is a toxic secondary metabolite produced by molds of the Fusarium genus and one of the most important mycotoxins in cereal commodities, which can be enriched from the contaminated grain by deoxynivalenol in the process of wet processing. In this work, graphene/ZnO hybrids has been successfully prepared via a simple one-step hydrothermal method and exhibited superior photocatalytic activity for the photodegradation of DON under the irradiation of UV light. The UV light photocatalytic activity of graphene/ZnO hybrid GZ0.3 was 3.1 times than pure ZnO and about 99% of DON (15 ppm) could be photodegraded within 30 min totally while there were three peaks of intermediate products appeared. The ESI/MS analysis confirmed the presence of DON and degradation product with the secondary mass spectrogram in the positive ESI mode. Overall, this work could provide new insights into the fabrication of graphene/ZnO hybrids composite as high performance photocatalysts and facilitate their application in the mycotoxin detoxification and environmental protection issues. [ABSTRACT FROM AUTHOR]

Novel visible-light-driven 2D-2D heterojunction photocatalysts was constructed based on 2D g-C 3 N 4 and exfoliated ultrathin K + Ca 2 Nb 3 O 10 − nanosheets, which is derived from Dion-Jacobson phase layer perovskites. The photocatalytic performance of the 2D-2D g-C 3 N 4 /K + Ca 2 Nb 3 O 10 − nanosheet heterojunctions was evaluated by the degradation of tetracycline hydrochloride under visible light irradiation. Compared with bare K + Ca 2 Nb 3 O 10 − and g-C 3 N 4 , the g-C 3 N 4 /K + Ca 2 Nb 3 O 10 − nanosheet heterojunctions exhibited considerably enhanced photocatalytic activity towards the degradation of tetracycline hydrochloride, which is about 6.6 and 1.8 times higher than that of pure K + Ca 2 Nb 3 O 10 − and g-C 3 N 4 , respectively. This enhanced activity can be mainly attributed to the synergistic effect of g-C 3 N 4 /K + Ca 2 Nb 3 O 10 − nanosheet heterojunctions with strong interfacial interaction and abundant 2D coupling interfaces, which could efficiently promote the photo-induced charge separation. The results of work demonstrated that construction of 2D-2D heterojunctions is an effective strategy to obtain the enhanced photocatalytic activity towards the degradation of tetracycline hydrochloride. [ABSTRACT FROM AUTHOR]

Novel visible-light-driven AgI/WO 3 nanocomposites were synthesized by a facile precipitation method. Multiple techniques were applied to investigate the structures, morphologies, optical and electronic properties and photocatalytic performance of as-prepared samples. The photocatalytic performance of the AgI/WO 3 nanocomposites was evaluated sufficiently by using colorless antibiotic agent tetracycline hydrochloride (TC). The optimum photocatalytic performance of TC photodegradation over 20%-AgI/WO 3 is as about 4.3 and 25 times high as that of pure AgI and WO 3 , respectively. The possible mechanism for the enhanced photocatalytic activity could be attributed to the formation of a redox-mediator-free direct Z-scheme system which causes the photogenerated electrons migrate from WO 3 to AgI, leading to effective charge separation of WO 3 . Furthermore, the stability and the possible mechanism of AgI/WO 3 nanocomposite photocatalysts for TC degradation are also elucidated. [ABSTRACT FROM AUTHOR]

Visible-driven photocatalysis plays a critical role in solar energy conversion, but the efficiency is limited by the poor charge separation and utilization. Here, a ternary photocatalyst is constructed using Cu-In-Zn-S quantum dots (CIZS QDs), MoS 2 and carbon dots (CDs). Interestingly, transient photovoltage measurements confirm that MoS 2 has no assistance on the charge extraction rate, whereas CDs dramatically increases the attenuation constant of the charge recombination process (from 0.178 to 0.260 ms) due to its electron sinking effect. The optimal hydrogen production rate of CIZS/MoS 2 /CDs reaches 3706 μmol g-1 h-1, which is 6.65 and 148.24 times to that of CIZS QDs and MoS 2 , respectively. Further electrocatalytic tests indicate that MoS 2 is the main place for hydrogen evolution reaction, whereas CIZS and CDs are responsible for light harvesting and charge sinking, respectively. This work provides a useful guideline for the synergy of charge extraction and utilization process in composite photocatalyst design. Carbon dots are used for mediating highly efficient charge sinking, resulting in the increase of attenuation constant of surface charge carriers from 0.178 to 0.260 ms and 6.65 times enhancement of hydrogen evolution rate in CIZS/MoS 2 /CDs. [Display omitted] • Carbon-dots-mediated highly efficient charge sinking in CIZS/MoS 2 /CDs photocatalyst for hydrogen evolution. • The hydrogen production rate over the CIZS/MoS 2 /CDs has 6.65-fold increase over primal CIZS. • The attenuation constant of the surface charge carriers in CIZS/MoS 2 /CDs increases from 0.178 to 0.260 ms. [ABSTRACT FROM AUTHOR]

• ZnIn 2 S 4 /KCa 2 Nb 3 O 10 nanosheet heterojunctions are constructed by in-situ solution-processed method. • The optimal sample shows significantly enhanced photocatalytic CO 2 reduction activity than bare ZnIn 2 S 4 and KCa 2 Nb 3 O 10. • The enhanced photocatalytic activity is ascribed to the improved charge separation efficiency of heterojunctions. ga1 Construction of heterojunctions with face-to-face contact is an excellent strategy for highly efficient photocatalytic CO 2 reduction system. Herein, ZnIn 2 S 4 /KCa 2 Nb 3 O 10 (ZnIn 2 S 4 /KCNO) 2D/2D nanosheet heterojunctions are fabricated via an in-situ solution-processed method, and the optimal 20%-ZnIn 2 S 4 /KCNO heterojunction shows a significantly enhanced photocatalytic activity with the CO production rate of 4.69 μmol g−1 h−1, which is about 12.31 and 1.95 times higher than that of bare ZnIn 2 S 4 and KCa 2 Nb 3 O 10 under simulated sunlight irradiation. The as-prepared ZnIn 2 S 4 /KCNO nanosheet heterojunctions exhibit tremendously improved charge transfer and separation efficiency. The ultrathin structure KCNO is conducive to the rapid transmission of photogenerated electrons, while the nanoflower-like structure ZnIn 2 S 4 is conducive to the full contact with the reactants to produce more protons, resulting in significantly boosted CO production performance. This work gives a new strategy to construct 2D/2D nanosheet heterojunctions for photocatalytic CO 2 conversion, which can offer significant inspirations for other 2D hybrid systems. [ABSTRACT FROM AUTHOR]