Atomic Interface Engineering of Single-Atom Pt/TiO2-Ti3C2 for Boosting Photocatalytic CO2 Reduction

Solar-driven CO₂ conversion into valuable fuels is a promising strategy to alleviate the energy and environmental issues. However, inefficient charge separation and transfer greatly limits the photocatalytic CO₂ reduction efficiency. Herein, single-atom Pt anchored on 3D hierarchical TiO₂-Ti₃C₂ with atomic-scale interface engineering is successfully synthesized through an in situ transformation and photoreduction method. The in situ growth of TiO₂ on Ti₃C₂ nanosheets can not only provide interfacial driving force for the charge transport, but also create an atomic-level charge transfer channel for directional electron migration. Moreover, the single-atom Pt anchored on TiO₂ or Ti₃C₂ can effectively capture the photogenerated electrons through the atomic interfacial Pt O bond with shortened charge migration distance, and simultaneously serve as active sites for CO₂ adsorption and activation. Benefiting from the synergistic effect of the atomic interface engineering of single-atom Pt and interfacial Ti O Ti, the optimized photocatalyst exhibits excellent CO₂-to-CO conversion activity of 20.5 µmol g⁻¹ h⁻¹ with a selectivity of 96%, which is five times that of commercial TiO₂ (P25). This work sheds new light on designing ideal atomic-scale interface and single-atom catalysts for efficient solar fuel conversation.     

Embedding Plasmonic Metal into Heterointerface of MOFs-Encapsulated Semiconductor Hollow Architecture for Boosting CO2 Photoreduction

Coupling hollow semiconductor with metal–organic frameworks (MOFs) holds great promise for constructing high-efficient CO₂ photoreduction systems. However, energy band mismatch between them makes it difficult to exert their advantages to maximize the overall photocatalytic efficiency, since that the blockage of desirable interfacial charge transfer gives rise to the enrichment of photoelectrons and CO₂ molecules on the different locations. Herein, an interfacial engineering is presented to overcome this impediment, based on the insertion of plasmonic metal into the heterointerfaces between them, forming a stacked semiconductor/metal@MOF photocatalyst. Experimental observations and theoretical simulations validate the critical roles of embedded Au in maneuvering the charge separation/transfer and surface reaction: (i) bridges the photoelectron transfer from hollow CdS (H-CdS) to ZIF-8; (ii) produces hot electrons and shifts them to ZIF-8; (iii) induces the formation of ZIF-8 defects in promoting the CO₂ adsorption/activation and transformation to CO with low energy barriers. Consequently, the as-prepared H-CdS/Au@ZIF-8 with optimal ZIF-8 thickness exhibits distinctly boosted activity and superb selectivity in CO production as compared with H-CdS@ZIF-8 and other counterparts. This work provides protocols to take full advantages of components involved for enhanced solar-to-chemical energy conversion efficiency of hybrid artificial photosynthetic systems through rationally harnessing the charge transfer between them.     

Guest-Induced Multilevel Charge Transport Strategy for Developing Metal-Organic Frameworks to Boost Photocatalytic CO2 Reduction

Encapsulating photogenerated charge-hopping nodes and space transport bridges within metal–organic frameworks (MOFs) is a promising method of boosting the photocatalytic performance. Herein, this work embeds electron transfer media (9,10-bis(4-pyridyl)anthracene (BPAN)) in MOF cavities to build multi-level electron transfer paths. The MOF cavities are accurately regulated to investigate the significance of the multi-level electron transfer paths in the process of CO₂ photoreduction by evaluating the difference in the number of guest media. The prepared MOFs, {[Co(BPAN)(1,4-dicarboxybenzene)(H₂O)₂]·BPAN·2H₂O} and {[Co(BPAN)₂(4,4′-biphenyldicarboxylic acid)₂(H₂O)₂]·2BPAN·2H₂O} (denoted as BPAN-Co-1 and BPAN-Co-2), exhibit efficient visible-light-driven CO₂ conversion properties. The CO photoreduction efficacy of BPAN-Co-2 (5598 µmol g⁻¹ h⁻¹) is superior to that of most reported MOF-based catalysts. In addition, the enhanced CO₂ photoreduction ability is supported by density functional theory (DFT). This work illustrates the feasibility of realizing charge separation characteristics in MOF catalysts at the molecular level, and provides new insight for designing high-performance MOFs for artificial photosynthesis.     

Strain-Engineering of Mesoporous Cs3Bi2Br9/BiVO4 S-Scheme Heterojunction for Efficient CO2 Photoreduction

Slow charge kinetics and unfavorable CO₂ adsorption/activation strongly inhibit CO₂ photoreduction. In this study, a strain-engineered Cs₃Bi₂Br₉/hierarchically porous BiVO₄ (s-CBB/HP-BVO) heterojunction with improved charge separation and tailored CO₂ adsorption/activation capability is developed. Density functional theory calculations suggest that the presence of tensile strain in Cs₃Bi₂Br₉ can significantly downshift the p-band center of the active Bi atoms, which enhances the adsorption/activation of inert CO₂. Meanwhile, in situ irradiation X-ray photoelectron spectroscopy and electron spin resonance confirm that efficient charge transfer occurs in s-CBB/HP-BVO following an S-scheme with built-in electric field acceleration. Therefore, the well-designed s-CBB/HP-BVO heterojunction exhibits a boosted photocatalytic activity, with a total electron consumption rate of 70.63 µmol g⁻¹ h⁻¹, and 79.66% selectivity of CO production. Additionally, in situ diffuse reflectance infrared Fourier transform spectroscopy reveals that CO₂ photoreduction undergoes a formaldehyde-mediated reaction process. This work provides insight into strain engineering to improve the photocatalytic performance of halide perovskite.     

Regulating π-Conjugation in sp2-Carbon-Linked Covalent Organic Frameworks for Efficient Metal-Free CO2 Photoreduction with H2O

The development of sp²-carbon-linked covalent organic frameworks (sp²c-COFs) as artificial photocatalysts for solar-driven conversion of CO₂ into chemical feedstock has captured growing attention, but catalytic performance has been significantly limited by their intrinsic organic linkages. Here, a simple, yet efficient approach is reported to improve the CO₂ photoreduction on metal-free sp²c-COFs by rationally regulating their intrinsic π-conjugation. The incorporation of ethynyl groups into conjugated skeletons affords a significant improvement in π-conjugation and facilitates the photogenerated charge separation and transfer, thereby boosting the CO₂ photoreduction in a solid-gas mode with only water vapor and CO₂. The resultant CO production rate reaches as high as 382.0 µmol g⁻¹ h⁻¹, ranking at the top among all additive-free CO₂ photoreduction catalysts. The simple modulation approach not only enables to achieve enhanced CO₂ reduction performance but also simultaneously gives a rise to extend the understanding of structure-property relationship and offer new possibilities for the development of new π-conjugated COF-based artificial photocatalysts.     

Defect engineering of photocatalysts for solar-driven conversion of CO2 into valuable fuels

Photoreduction of CO₂ into valuable fuels is a clean and sustainable way to mitigate the energy crisis and environmental problems. Factors limiting the efficiency of CO₂ photoreduction include narrow-band light absorption, poor charge carrier separation and transport, and sluggish activation/reaction of CO₂ on the surface of photocatalyst. In recent years, defect engineering of photocatalysts emerges as an effective method to improve their efficiency in the photocatalytic conversion of CO₂ into useful fuels. This review is focused on discussing how structural defects can be used to modulate the electronic structure of the photocatalysts and activate the inert CO₂ molecules. Special emphasis is placed on the important impact of defects on the charge carrier dynamics of the photocatalysts. Our discussions cover a variety of defective semiconductors, including metal oxides, metal sulfides, and two dimensional materials. In addition, the challenges and prospects of defect engineering in photoreduction of CO₂ are also analyzed. This review aims to provide useful information about the fundamental principles of photoreduction of CO₂ and guidance on the design and preparation of defective photocatalysts.     

State-of-the-art advancements of crystal facet-exposed photocatalysts beyond TiO2: Design and dependent performance for solar energy conversion and environment applications

Tailoring semiconductor crystals with optimized reactive facets is considered one of effective strategies to improve photocatalytic activity and selectivity for energy conversion and environmental remediation. The arrangement of surface atom structure through crystal facet engineering could tune surface free energy, electronic band structure, charge transfer and separation, the reactant adsorption and product desorption, and surface redox sites. This progress report aims to concisely highlight recent state-of-the-art progress of crystal facet-dependent performance of promising photocatalysts beyond TiO₂. It includes (1) design of crystal-facet exposed photocatalysts with various routes through altering the relative order of the surface energy; (2) crystal facet-based surface junctions to promote the charge transfer and separation; (3) in situ techniques to detection of charge accumulation on crystal-faceted surfaces; (4) exposed face-determined photocatalytic application in water splitting, photoreduction of CO₂ into renewable fuels, degradation of organic contaminants from the point of the reactant adsorption and activation. The challenges and prospects for future development are also presented.     

Enhanced Interfacial Charge Transfer/Separation By LSPR-Induced Defective Semiconductor Toward High Co2RR Performance

Solar-driven reduction of CO₂ emissions into high-value-added carbonaceous compounds has been recognized as a sustainable energy conversion way. The high-efficiency charge separation and effective activation are the critical issues in the process. The local plasma effect of metal and the vacancy of semiconductors in the metal-semiconductor heterostructure can solve this issue extensively. Herein, an oxygen vacancy photocatalyst containing uniform Ag nanoparticles (Ag-20@Nb₂O_5-x) is designed, which exhibits an excellent reduction performance and the CO yield can reach 59.13 µmol g⁻¹ with high selectivity. The carrier migration is accelerated and the activation of CO₂ is facilitated by the local surface plasmon effect and oxygen vacancy. Moreover, the photocatalytic CO₂ reduction mechanism is revealed based on the density functional theory and in situ technology in detail. This work provides an in-depth understanding of the design of more ingenious metal-semiconductor photocatalysts to achieve more efficient charge transfer.     

High-Dispersive Pd Nanoparticles on Hierarchical N-Doped Carbon Nanocages to Boost Electrochemical CO2 Reduction to Formate at Low Potential

Electrochemical CO₂ reduction reaction (CO₂RR) to value-added chemicals/fuels is an effective strategy to achieve the carbon neutral. Palladium is the only metal to selectively produce formate via CO₂RR at near-zero potentials. To reduce cost and improve activity, the high-dispersive Pd nanoparticles on hierarchical N-doped carbon nanocages (Pd/hNCNCs) are constructed by regulating pH in microwave-assisted ethylene glycol reduction. The optimal catalyst exhibits high formate Faradaic efficiency of >95% within −0.05–0.30 V and delivers an ultrahigh formate partial current density of 10.3 mA cm⁻² at the low potential of −0.25 V. The high performance of Pd/hNCNCs is attributed to the small size of uniform Pd nanoparticles, the optimized intermediates adsorption/desorption on modified Pd by N-doped support, and the promoted mass/charge transfer kinetics arising from the hierarchical structure of hNCNCs. This study sheds light on the rational design of high-efficient electrocatalysts for advanced energy conversion.     

Engineering Single Cu Sites into Covalent Organic Framework for Selective Photocatalytic CO2 Reduction

Photocatalytic CO₂ conversion into value-added chemicals is a promising route but remains challenging due to poor product selectivity. Covalent organic frameworks (COFs) as an emerging class of porous materials are considered as promising candidates for photocatalysis. Incorporating metallic sites into COF is a successful strategy to realize high photocatalytic activities. Herein, 2,2′-bipyridine-based COF bearing non-noble single Cu sites is fabricated by chelating coordination of dipyridyl units for photocatalytic CO₂ reduction. The coordinated single Cu sites not only significantly enhance light harvesting and accelerate electron–hole separation but also provide adsorption and activation sites for CO₂ molecules. As a proof of concept, the Cu-Bpy-COF as a representative catalyst exhibits superior photocatalytic activity for reducing CO₂ to CO and CH₄ without photosensitizer, and impressively, the product selectivity of CO and CH₄ can be readily modulated only by changing reaction media. Experimental and theoretical results reveal the crucial role of single Cu sites in promoting photoinduced charge separation and solvent effect in regulating product selectivity, which provides an important sight onto the design of COF photocatalysts for selective CO₂ photoreduction.     

Synergy-Compensation Effect of Ferroelectric Polarization and Cationic Vacancy Collaboratively Promoting CO2 Photoreduction

Photocatalytic CO₂ reduction is severely limited by the rapid recombination of photo-generated charges and insufficient reactive sites. Creating electric field and defects are effective strategies to inhibit charge recombination and enrich catalytic sites, respectively. Herein, a coupled strategy of ferroelectric poling and cationic vacancy is developed to achieve high-performance CO₂ photoreduction on ferroelectric Bi₂MoO₆, and their interesting synergy-compensation relationship is first disclosed. Corona poling increases the remnant polarization of Bi₂MoO₆ to enhance the intrinsic electric field for promoting charge separation, while it decreases the CO₂ adsorption. The introduced Mo vacancy (V_Mo) facilitates the adsorption and activation of CO₂, and surface charge separation by creating local electric field. Unfortunately, V_Mo largely reduces the remnant polarization intensity. Coupling poling and V_Mo not only integrate their advantages, resulting in an approximately sevenfold increased surface charge transfer efficiency, but also compensate for their shortcomings, for example, V_Mo largely alleviates the negative effects of ferroelectric poling on CO₂ adsorption. In the absence of co-catalyst or sacrificial agent, the poled Bi₂MoO₆ with V_Mo exhibits a superior CO₂-to-CO evolution rate of 19.75 µmol g⁻¹ h⁻¹, ≈8.4 times higher than the Bi₂MoO₆ nanosheets. This work provides new ideas for exploring the role of polarization and defects in photocatalysis.     

The Effect of Materials Architecture in TiO2/MOF Composites on CO2 Photoreduction and Charge Transfer

CO₂ photoreduction to C₁/C₁₊ energized molecules is a key reaction of solar fuel technologies. Building heterojunctions can enhance photocatalysts performance, by facilitating charge transfer between two heterojunction phases. The material parameters that control this charge transfer remain unclear. Here, it is hypothesized that governing factors for CO₂ photoreduction in gas phase are: i) a large porosity to accumulate CO₂ molecules close to catalytic sites and ii) a high number of “points of contact” between the heterojunction components to enhance charge transfer. The former requirement can be met by using porous materials; the latter requirement by controlling the morphology of the heterojunction components. Hence, composites of titanium oxide or titanate and metal–organic framework (MOF), a highly porous material, are built. TiO₂ or titanate nanofibers are synthesized and MOF particles are grown on the fibers. All composites produce CO under UV–vis light, using H₂ as reducing agent. They are more active than their component materials, e.g., ≈9 times more active than titanate. The controlled composites morphology is confirmed and transient absorption spectroscopy highlights charge transfer between the composite components. It is demonstrated that electrons transfer from TiO₂ into the MOF, and holes from the MOF into TiO₂, as the MOF induces band bending in TiO₂.     

Cocatalysts in Semiconductor‐based Photocatalytic CO2 Reduction: Achievements,Challenges, and Opportunities

Ever‐increasing fossil‐fuel combustion along with massive CO₂ emissions has aroused a global energy crisis and climate change. Photocatalytic CO₂ reduction represents a promising strategy for clean, cost‐effective, and environmentally friendly conversion of CO₂ into hydrocarbon fuels by utilizing solar energy. This strategy combines the reductive half‐reaction of CO₂ conversion with an oxidative half reaction, e.g., H₂O oxidation, to create a carbon‐neutral cycle, presenting a viable solution to global energy and environmental problems. There are three pivotal processes in photocatalytic CO₂ conversion: (i) solar‐light absorption, (ii) charge separation/migration, and (iii) catalytic CO₂ reduction and H₂O oxidation. While significant progress is made in optimizing the first two processes, much less research is conducted toward enhancing the efficiency of the third step, which requires the presence of cocatalysts. In general, cocatalysts play four important roles: (i) boosting charge separation/transfer, (ii) improving the activity and selectivity of CO₂ reduction, (iii) enhancing the stability of photocatalysts, and (iv) suppressing side or back reactions. Herein, for the first time, all the developed CO₂‐reduction cocatalysts for semiconductor‐based photocatalytic CO₂ conversion are summarized, and their functions and mechanisms are discussed. Finally, perspectives in this emerging area are provided.     

In Situ Constructed Perovskite–Chalcogenide Heterojunction for Photocatalytic CO2 Reduction

Perovskite nanocrystals (PNCs) are promising candidates for solar-to-fuel conversions yet exhibit low photocatalytic activities mainly due to serious recombination of photogenerated charge carriers. Constructing heterojunction is regarded as an effective method to promote the separation of charge carriers in PNCs. However, the low interfacial quality and non-directional charge transfer in heterojunction lead to low charge transfer efficiency. Herein, a CsPbBr₃–CdZnS heterojunction is designed and prepared via an in situ hot-injection method for photocatalytic CO₂ reduction. It is found that the high-quality interface in heterojunction and anisotropic charge transfer of CdZnS nanorods (NRs) enable efficient spatial separation of charge carriers in CsPbBr₃–CdZnS heterojunction. The CsPbBr₃–CdZnS heterojunction achieves a higher CO yield (55.8 µmol g⁻¹ h⁻¹) than that of the pristine CsPbBr₃ NCs (13.9 µmol g⁻¹ h⁻¹). Furthermore, spectroscopic experiments and density functional theory (DFT) simulations further confirm that the suppressed recombination of charge carriers and lowered energy barrier for CO₂ reduction contribute to the improved photocatalytic activity of the CsPbBr₃–CdZnS heterojunction. This work demonstrates a valid method to construct high-quality heterojunction with directional charge transfer for photocatalytic CO₂ reduction. This study is expected to pave a new avenue to design perovskite–chalcogenide heterojunction.     

Direct Conversion of Rice Husks to Nanostructured SiC/C for CO2 Photoreduction

A one-step and template-free synthesis of a SiC nanowires/C (SiC-NW/C) composite from rice husks (RHs) is realized via a molten-salt-assisted electrochemical method. The process integrates simultaneously carbonization, electrodeoxidation, nanostructuring, and self-purification for converting RHs to a SiC-NW/C hybrid that is assembled from SiC NWs embedded in porous N-doped graphitic carbon with strong coupling. The SiC-NW/C nanostructure enables efficient CO₂ adsorption and fast separation and transfer of charge carriers. Benefiting from the structural and compositional merits, the SiC-NW/C composite shows superior activity for photoreduction of CO₂ to CO, in the absence of any additional cocatalysts or sacrificial agents. The process proposed herein might help to bridge a closed-loop carbon cycle in the whole production–utilization of biomass.     

Promoted Photocharge Separation in 2D Lateral Epitaxial Heterostructure for Visible-Light-Driven CO2 Photoreduction

Photocarrier recombination remains a big barrier for the improvement of solar energy conversion efficiency. For 2D materials, construction of heterostructures represents an efficient strategy to promote photoexcited carrier separation via an internal electric field at the heterointerface. However, due to the difficulty in seeking two components with suitable crystal lattice mismatch, most of the current 2D heterostructures are vertical heterostructures and the exploration of 2D lateral heterostructures is scarce and limited. Here, lateral epitaxial heterostructures of BiOCl @ Bi₂O₃ at the atomic level are fabricated via sonicating-assisted etching of Cl in BiOCl. This unique lateral heterostructure expedites photoexcited charge separation and transportation through the internal electric field induced by chemical bonding at the lateral interface. As a result, the lateral BiOCl @ Bi₂O₃ heterostructure demonstrates superior CO₂ photoreduction properties with a CO yield rate of about 30 µmol g⁻¹ h⁻¹ under visible light illumination. The strategy to fabricate lateral epitaxial heterostructures in this work is expected to provide inspiration for preparing other 2D lateral heterostructures used in optoelectronic devices, energy conversion, and storage fields.     

Macroscopic Spontaneous Polarization and Surface Oxygen Vacancies Collaboratively Boosting CO2 Photoreduction on BiOIO3 Single Crystals

Prompt recombination of photogenerated electrons and holes in bulk and on the surface of photocatalysts harshly impedes the photocatalytic efficiency. However, the simultaneous manipulation of photocharges in the two locations is challenging. Herein, the synchronous promotion of bulk and surface separation of photoinduced charges for prominent CO₂ photoreduction by coupling macroscopic spontaneous polarization and surface oxygen vacancies (OVs) of BiOIO₃ single crystals is reported. The oriented growth of BiOIO₃ single-crystal nanostrips along the [001] direction, ensuing substantial well-aligned IO₃ polar units, renders a large enhancement for the macroscopic polarization electric field, which is capable of driving the rapid separation and migration of charges from bulk to surface. Meanwhile the introduction of surface OVs establishes a local electric field for charge migration to catalytic sites on the surface of BiOIO₃ nanostrips. Highly polarized BiOIO₃ nanostrips with ample OVs demonstrate outstanding CO₂ reduction activity for CO production with a rate of 17.33 µmol g⁻¹ h⁻¹ (approximately ten times enhancement) without any sacrificial agents or cocatalysts, being one of the best CO₂ reduction photocatalysts in the gas–solid system reported so far. This work provides an integrated solution to governing charge movement behavior on the basis of collaborative polarization from bulk and surface.     

Plasmonic Metal Mediated Charge Transfer in Stacked Core–Shell Semiconductor Heterojunction for Significantly Enhanced CO2 Photoreduction

Construction of core–shell semiconductor heterojunctions and plasmonic metal/semiconductor heterostructures represents two promising routes to improved light harvesting and promoted charge separation, but their photocatalytic activities are respectively limited by sluggish consumption of charge carriers confined in the cores, and contradictory migration directions of plasmon-induced hot electrons and semiconductor-generated electrons. Herein, a semiconductor/metal/semiconductor stacked core–shell design is demonstrated to overcome these limitations and significantly boost the photoactivity in CO₂ reduction. In this smart design, sandwiched Au serves as a “stone”, which “kills two birds” by inducing localized surface plasmon resonance for hot electron generation and mediating unidirectional transmission of conduction band electrons and hot electrons from TiO₂ core to MoS₂ shell. Meanwhile, upward band bending of TiO₂ drives core-to-shell migration of holes through TiO₂–MoS₂ interface. The co-existence of TiO₂ → Au → MoS₂ electron flow and TiO₂ → MoS₂ hole flow contributes to spatial charge separation on different locations of MoS₂ outer layer for overall redox reactions. Additionally, reduction potential of photoelectrons participating in the CO₂ reduction is elaborately adjusted by tuning the thickness of MoS₂ shell, and thus the product selectivity is delicately regulated. This work provides fresh hints for rationally controlling the charge transfer pathways toward high-efficiency CO₂ photoreduction.     

Semiconductor Quantum Dots: An Emerging Candidate for CO2 Photoreduction

As one of the most critical approaches to resolve the energy crisis and environmental concerns, carbon dioxide (CO₂) photoreduction into value‐added chemicals and solar fuels (for example, CO, HCOOH, CH₃OH, CH₄) has attracted more and more attention. In nature, photosynthetic organisms effectively convert CO₂ and H₂O to carbohydrates and oxygen (O₂) using sunlight, which has inspired the development of low‐cost, stable, and effective artificial photocatalysts for CO₂ photoreduction. Due to their low cost, facile synthesis, excellent light harvesting, multiple exciton generation, feasible charge‐carrier regulation, and abundant surface sites, semiconductor quantum dots (QDs) have recently been identified as one of the most promising materials for establishing highly efficient artificial photosystems. Recent advances in CO₂ photoreduction using semiconductor QDs are highlighted. First, the unique photophysical and structural properties of semiconductor QDs, which enable their versatile applications in solar energy conversion, are analyzed. Recent applications of QDs in photocatalytic CO₂ reduction are then introduced in three categories: binary II–VI semiconductor QDs (e.g., CdSe, CdS, and ZnSe), ternary I–III–VI semiconductor QDs (e.g., CuInS₂ and CuAlS₂), and perovskite‐type QDs (e.g., CsPbBr₃, CH₃NH₃PbBr₃, and Cs₂AgBiBr₆). Finally, the challenges and prospects in solar CO₂ reduction with QDs in the future are discussed.     

Remarkable Improvement in Photocatalytic Performance for Tannery Wastewater Processing via SnS2 Modified with N‐Doped Carbon Quantum Dots: Synthesis,Characterization, and 4‐Nitrophenol‐Aided Cr(VI) Photoreduction

Photocatalytic pathways are proved crucial for the sustainable production of chemicals and fuels required for a pollution‐free planet. Electron–hole recombination is a critical problem that has, so far, limited the efficiency of the most promising photocatalytic materials. Here, the efficacy of the 0D N doped carbon quantum dots (N‐CQDs) is demonstrated in accelerating the charge separation and transfer and thereby boosting the activity of a narrow‐bandgap SnS₂ photocatalytic system. N‐CQDs are in situ loaded onto SnS₂ nanosheets in forming N‐CQDs/SnS₂ composite via an electrostatic interaction under hydrothermal conditions. Cr(VI) photoreduction rate of N‐CQDs/SnS₂ is highly enhanced by engineering the loading contents of N‐CQDs, in which the optimal N‐CQDs/SnS₂ with 40 mol% N‐CQDs exhibits a remarkable Cr(VI) photoreduction rate of 0.148 min^?1, about 5‐time and 148‐time higher than that of SnS₂ and N‐CQDs, respectively. Examining the photoexcited charges via zeta potential, X‐ray photoelectron spectroscopy (XPS), surface photovoltage, and electrochemical impedance spectra indicate that the improved Cr(VI) photodegradation rate is linked to the strong electrostatic attraction between N‐CQDs and SnS₂ nanosheets in composite, which favors efficient carrier utilization. To further boost the carrier utilization, 4‐nitrophenol is introduced in this photocatalytic system and the efficiency of Cr(VI) photoreduction is further promoted.