Surface Catalytic Reactions Research Articles

ZnIn2S4 nanosheets with geometric defects for enhanced solar-driven hydrogen evolution and wastewater treatment

The key to development of high-performance and low cost photocatalysts hydrogen evolution and waste degradation is to realize efficient photo-generated charge carrier separation and surface catalytic reaction simultaneously without noble metal co-catalyst. To achieve this goal, a noble metal free ZnIn2S4 photocatalyst with geometric defects has been constructed, in which [In-S]4 tetrahedral vacancies (named as (InS)v) on the surface are created by removing the In and S atoms. Further mechanistic investigation has revealed that the (InS)v not only works as the active sites for reductive reaction, but also improves photo-generated electron-hole separation. As a result, the solar-driven hydrogen evolution rate reaches 10.70 mmol/gh without co-catalyst after optimizing the densities of the (InS)v. The apparent quantum efficiency at 380 nm, 395 nm, 420 nm, 450 nm and 520 nm is as high as 14.0 %, 17.1 %, 12.1 %, 8.2 % and 2.4 %, respectively. In addition, these photocatalysts also achieve a rate of 97.78 % and 91.27 % of RhB and MO within 3 and 60 min, respectively. This work show-case a novel approach to develop dual functional and noble metal free photocatalysts for efficiently utilizing solar energy for hydrogen generation and wastewater treatment.

Removal of arsenic from aqueous solution using magnetic biochar derived from Spirulina platensis

Arsenic contamination in surface waters and groundwater affects millions of people on a daily basis. Oxidation of As(III) to less toxic As(V) is a widely used strategy to enhance the removal of As from solution. This study developed and evaluated a Fe-modified biochar (FeSP600). Spirulina platensis (SP) is one of the most promising microalgae because of its physicochemical properties and potential applications. The high N content of SP may affect the physicochemical properties of the biochar, which could be used as an inherent N source for N doping biochar by carbonization. After Fe modification, the formed Fe species and N-containing components of SP were used to introduce pyridinic N, which can be coordinated with Fe to form Fe-N. We demonstrated that the formed Fe species (Fe0, Fe2+ and Fe3+) and the defective structures in FeSP600 could act as active sites for surface catalytic reactions. FeSP600 not only had magnetic properties but also could effectively remove As from an aqueous solution. These properties were attributed to the release of Fe2+ and the reactive oxygen species (ROSs) generated by the γ-Fe2O3 particles on the crystalline defect structure. As(III) and As(V) removal were affected by the initial pH values. The removal efficiencies for As(III) increased from 57.2 % to 94.9 % as the pH increased from 3 to 9, whereas that for As(V) decreased from 80.1 % to 46.8 %. The presence of coexisting ions either completely (PO43−) or partially (Cl−, CO32− and SO42−) inhibited As removal. The removal of As(V) depended on electrostatic interactions, but As(III) removal was a complex process, including both oxidation and surface adsorption, as the ROSs were able to oxidize As(III) to As(V). Our study demonstrates that FeSP600 has properties that are beneficial for the removal of As(III) and As(V) from aqueous environments. The findings of this study have potential for real-world application in treating As-contaminated water sources, particularly in improving drinking water purification systems in developing countries. More importantly, an assessment of the impact of FeSP600 usage on aquatic ecosystems is required to ensure the safe application of this technology. Therefore, developing methods for mass production of FeSP600 is essential for the commercialization of this technology, necessitating process engineering studies in this area.

Influence of inclined magnetic field and surface catalyzed reactions on a ternary hybrid nanofluid rotating flow with irreversibility analysis

Influence of inclined magnetic field and surface catalyzed reactions on a ternary hybrid nanofluid rotating flow with irreversibility analysis

Experiment and density functional theory researches on (Mn, Hf) co-doped Ce-based applied surface catalysts for carbon monoxide oxidation and thermal stability

Catalyst addition can improve system after treatment efficiency of pollutants purification. In this study, the performance of (Mn, Hf) co-doped Ce-based catalysts has been investigated in oxidation to mitigate CO emission of engines. A series of Ce-Mn-Hf-Ox with different metal ratios (Ce: Mn: Hf = 8:1:1,7:2:1,7:1:2,6:1:3,6:2:2 and 6:3:1) catalysts were prepared. DFT (density functional theory) calculations were carried out to investigate the mechanism of applied surface catalytic reaction. XRD (X-ray Diffraction) analysis and SEM (Scanning Electron Microscope) revealed Mn and Hf doping increased the catalysts surface area contact with the CO gas with the catalytic performance improvement. XPS (X-ray Photoelectron Spectra), H2-TPR (Temperature-Programmed Reduction) and DFT calculations manifested the Mn and Hf doping would promote the formation of oxygen vacancy to enhance the catalytic performance for CO oxidation. The thermal stability of the catalysts increased with Hf content increasement. Ce6Mn3Hf1 had the highest catalytic activity with the favorable thermal stability according to the temperature-programmed oxidation of CO experiment. T10, T50 and T90 of CO oxidation were 156, 188 and 198 °C, which lost 4.82 % mass at 500°C and 6.18 % mass at 900 °C. Ce6Mn1Hf3Ox displayed the best thermal stability according to TG with the lowest catalytic activity.

Development of Air–Ti Gas-Surface Reaction Mechanisms and Rate Calculations

Gas-surface reaction mechanisms and rates were developed for an air–titanium surface to support finite-rate catalytic surface reaction models used in computational fluid dynamics. For the surface dissociation/recombination reactions, a two-step reaction method was applied based on the assumption that two atoms must be positioned in adjacent cells to recombine. Transition state theory was used to calculate the surface reactions for adsorbed diatomic molecules to dissociate to the adjacent unit cell or atoms located in the adjacent cells to recombine into diatomic molecules. For the second step, atoms located in the adjacent cells are allowed to further dissociate to another cell (total separation), or totally separated atoms recombine into the adjacent cells. A stochastic gas-surface kinetics simulation code, STOKIN, was developed to simulate gas-surface reactions and to calculate the equilibrium constants of second molecular dissociation ⇌ recombination processes. Thermodynamic properties of the adsorbates (enthalpies, entropies, and heat capacities) were calculated using density functional theory along with statistical mechanics assuming no rotational and translational contributions to the entropies and heat capacities due to the adsorbates’ inability to freely move or rotate on the surface.

Surface-Integrating Oxygen Vacancy and CuxO Nanodots Enabling Synergistic Electric Field and Dual Catalytic Sites Boosting CO2 Photoreduction.

High carrier separation efficiency and rapid surface catalytic reaction are crucial for enhancing catalytic CO2 photoreduction reaction. Herein, integrated surface decoration strategy with oxygen vacancies (Ov) and anchoring CuxO (1 < x < 2) nanodots below 10nm is realized on Bi2MoO6 for promoting CO2 photoreduction performance. The charge interaction between Ov and anchored CuxO enables the formation of enhanced internal electric field, which provides a strong driving force for accelerating the separation of photocharge carriers on the surface of Bi2MoO6 (ηsurf ≈71%). They can also cooperatively reduce the surface work function of Bi2MoO6, facilitating the migration of carrier to the surface. Meanwhile, surface-integrated Ov and CuxO nanodots allowing dual catalytic sites strengthens the adsorption and activation CO2 into *CO2 over Bi2MoO6, considerably boosting the progression of CO2 conversion process. In the absence of co-catalyst or sacrificial agent, Bi2MoO6 with Ov and CuxO nanodots achieves a photocatalytic CO generation rate of 12.75µmol g-1 h-1, a remarkable increase of over ≈15 times that of the original counterpart. This work provides a new idea for governing charge movement behaviors and catalytic reaction thermodynamics on the basis of synergistic improvement of electric field and active sites by coupling of the internal defects and external species.

Oxidation cocatalyst/S-scheme junction cooperatively assists photocatalytic H2 production in ternary hybrid: The case of PdO@TiO2-Cu2O

Solar-driven photocatalytic hydrogen production from water splitting holds significant potential in addressing the energy crisis and environmental pollution. However, rapid recombination of photogenerated carriers and insufficient surface catalytic reaction kinetics hinder the photocatalytic process. Constructing the catalytic systems with multi-channel charge-separation can effectively alleviate those issues. In this work, ternary PdO@TiO2-Cu2O composites have been synthesized through precursor calcination and low-temperature reduction, where PdO and Cu2O nanoparticles couple with the TiO2 nanorods. Comparing to single TiO2, binary PdO@TiO2 and TiO2-Cu2O, the PdO@TiO2-Cu2O hybrid exhibits enhanced photocatalytic hydrogen production performance (5831μmol g-1h−1), with a hydrogen production rate more than three times that of single TiO2. Based on the band structures of TiO2 and Cu2O, along with the photochemical/electrochemical, in-situ EPR, Photoluminescence (PL) tests, and work function calculations, the formation of an S-scheme heterojunction at the TiO2-Cu2O interface under light illumination facilitates the recombination of electrons in the conduction band (CB) of TiO2 with holes in the valence band (VB) of Cu2O. In this regard, the established built-in electric field significantly accelerates the transfer of photogenerated charges while preserving their respective strong oxidation and reduction capabilities. Meanwhile, the introduction of PdO enriches the holes and further enhances the rate of charge separation. This S-scheme heterojunction with directional charge transfer and oxidation cocatalyst collectively form multi-channels of charge separation, optimizing charge migration and enabling efficient hydrogen production, thus improving the photocatalytic capability of pristine TiO2. This study provides a rational approach to construct efficient S-scheme heterojunction/oxidation cocatalyst multi-component catalytic systems for water splitting into hydrogen.

Revealing the Effect of Electronic Configuration in Cux Species on CO2 Photoreduction Characteristic Products.

As of the present time, the in-depth study of the structure-activity relationship between electronic configuration and CO2 photoreduction performance is often overlooked. Herein, a series of Cux species modified CeO2 nanodots are constructed in situ by flame spray pyrolysis (FSP) to achieve an efficient photocatalytic CO2-to-C2 conversion with an electron utilization of up to 142.5µmol g-1. Through an in-depth study of the electronic behavior and catalytic pathways, it is found that the Cu0/Cu+ species in the coexistence state of Cu0/Cu+/Cu2+ can optimize the energy band structure, photocurrent stability, and provide a kinetic basis for the active surface catalytic reaction process that requires the conversion of multiple electrons into C2 products, which ultimately enhances the CO2-to-C2H6 photoreduction by 3.8-fold and that for CO2-to-C2H4 photoreduction by 5.2-fold. Besides, the Cu2+ species in the coexistence state of Cu0/Cu+/Cu2+ are able to regulate the electronic behavior and the choice of the catalytic pathway, enabling the transitions between CO2-to-C2H6 and CO2-to-C2H4. This work indicates that electronic configuration optimization is an effective strategy to significantly enhance the CO2 photoreduction performance and provides new ideas for the design and synthesis of high-performance heterostructure photocatalysts.

CFD modeling using reactions kinetics for selective hydrogenation for acetylene in a fixed-bed reactor

Selective hydrogenation of acetylene (SHA) reactions is usually performed in fixed-bed reactors (FBR). The traditional SHA kinetics, when coupled with a three-dimensional computational fluid dynamics (CFD) model, requires improvement to accurately predict SHA reaction outcomes. The SHA microdynamics, when integrated with a three-dimensional CFD model, have not been comprehensively examined. In this paper, a mathematical model based on CFD was developed to simulate the reactive flow behavior of SHA in FBR using a novel OleMax100 catalyst. In this study, a 3D catalyst bed numerical simulation of FBR with coupled microdynamics description of conjugate heat transfer and surface catalytic reaction was carried out, and the accuracy of CFD at different Reynolds numbers (Re) was verified by experimental results, which showed a high degree of agreement between the model and experimental results. The effect of the ratio of tube to pellet diameter (D/d=N) on the fluid flow characteristics and SHA reaction in the bed was investigated, and the catalyst shape was considered. The simulation results show that an increase in N significantly improves the homogeneity of the flow field and the heat and mass transfer between the phases in the FBR, which leads to an increase in the conversion efficiency of acetylene. When N was increased from 4.00 to 6.67, the conversion was enhanced by 6.7 %. Increasing the Re value affects the reactivity, and the SHA reaction exists in a reaction zone where excessive residence time exacerbates the decrease in selectivity. The adopted and novel catalyst microkinetic models can provide some theoretical guidance for the optimal design of the SHA reaction and process improvement in FBR.

Fabrication of Novel Carbon-based Polymers by On-surface Cycloaromatization of Isopropyl Substituents

Surface-catalyzed reactions have been employed for the synthesis of carbon nanomaterials featuring precisely defined atomic structures. A recent breakthrough involves the gold surface-catalyzed [3 + 3] cycloaromatization of isopropyl-substituted arenes, allowing for on-surface synthesis of novel carbon-based polymers[1-3]. In this process, the surface plays a crucial role in activating the isopropyl substituents, facilitating the formation of phenylene rings through intermolecular coupling. For instance, such investigations might open new avenues in the field of carbon magnetism, which has gained an increased attention in view of the recent progress made in the synthesis and characterization of open-shell polycyclic aromatic hydrocarbons[2]. Under this scenario, the comprehensive fabrication of magnetic polymers emerges as a highly appealing field of research.Here, we introduce exemplary approaches toward the bottom-up fabrication of different carbon-based polymers homocoupled via surface-catalyzed [3 + 3] cycloaromatization of isopropyl substituents studied on Au(111) under ultra-high vacuum (UHV) conditions. The chemical structures of the polymers have been clearly elucidated by non-contact atomic force microscopy (nc-AFM). Scanning tunneling spectroscopy (STS), complemented by computational investigations reveals their ground state. Our approach can be a highly relevant step towards the on-surface synthesis of covalently linked 1D organic polymers with prospects in sensing, catalysis and nanoscale spintronic devices.

Direct Microenvironment Modulation of CO2 Electroreduction: Negatively Charged Ag Sites Going beyond Catalytic Surface Reactions.

Electrochemical reduction of CO2 is an important way to achieve carbon neutrality, and much effort has been devoted to the design of active sites. Apart from elevating the intrinsic activity, expanding the functionality of active sites may also boost catalytic performance. Here we designed "negatively charged Ag (nc-Ag)" active sites featuring both the intrinsic activity and the capability of regulating microenvironment, through modifying Ag nanoparticles with atomically dispersed Sn species. Different from conventional active sites (which only mediate the surface processes by bonding with the intermediates), the nc-Ag sites could also manipulate environmental species. Therefore, the sites could not only activate CO2, but also regulate interfacial H2O and CO2, as confirmed by operando spectroscopies. The catalyst delivers a high current density with a CO faradaic efficiency of 97 %. Our work here opens up new opportunities for the design of multifunctional electrocatalytic active sites.

Direct Microenvironment Modulation of CO2 Electroreduction: Negatively Charged Ag Sites Going beyond Catalytic Surface Reactions

AbstractElectrochemical reduction of CO2 is an important way to achieve carbon neutrality, and much effort has been devoted to the design of active sites. Apart from elevating the intrinsic activity, expanding the functionality of active sites may also boost catalytic performance. Here we designed “negatively charged Ag (nc‐Ag)” active sites featuring both the intrinsic activity and the capability of regulating microenvironment, through modifying Ag nanoparticles with atomically dispersed Sn species. Different from conventional active sites (which only mediate the surface processes by bonding with the intermediates), the nc‐Ag sites could also manipulate environmental species. Therefore, the sites could not only activate CO2, but also regulate interfacial H2O and CO2, as confirmed by operando spectroscopies. The catalyst delivers a high current density with a CO faradaic efficiency of 97 %. Our work here opens up new opportunities for the design of multifunctional electrocatalytic active sites.

Nanoscopic catalyst-loaded porous metal oxide hollow frameworks using porous block copolymer templates for high performance formaldehyde sensors

Porous and hollow nanostructures functionalized with nanoscopic catalysts have attracted considerable interest in a wide range of applications depending on surface reactions. In this study, we present an efficient and versatile synthetic strategy of porous metal oxide hollow frameworks (HFs) decorated with noble metal nanoparticles (NPs). The key lies in the use of porous and bicontinuous polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) microparticles as templates, which feature pores on the order of several hundred nanometers in size. Homogeneous Pt loading on the surface of the porous microparticles is achieved through the preferential adsorption of Pt precursors onto the P4VP block via electrostatic interactions. Subsequent SnO2 thin film deposition and calcination ultimately yield honeycomb-like SnO2 HFs with macropores and uniform distribution of Pt NPs. The Pt NP-loaded SnO2 HFs exhibit exceptional formaldehyde (HCHO) sensing capabilities, characterized by remarkable sensitivity (31.4 at 5 ppm), rapid response time (4.7 s at 5 ppm), ultra-low detection limit of 10 ppb, and remarkable cross-selectivity. These outstanding features result from their high surface area, gas permeability within porous hollow structures, and well-dispersed Pt NPs, which catalytically activate the sensor. Our study provides great promise for advancing surface catalytic reactions due to their exceptional surface area and gas permeability, paving the way for future applications.

H2-D2 Exchange Activity and Electronic Structure of Ag x Pd1-x Alloy Catalysts Spanning Composition Space.

Many computational studies of catalytic surface reaction kinetics have demonstrated the existence of linear scaling relationships between physical descriptors of catalysts and reaction barriers on their surfaces. In this work, the relationship between catalyst activity, electronic structure, and alloy composition was investigated experimentally using a Ag x Pd1-x Composition Spread Alloy Film (CSAF) and a multichannel reactor array that allows measurement of steady-state reaction kinetics at 100 alloy compositions simultaneously. Steady-state H2-D2 exchange kinetics were measured at atmospheric pressure on Ag x Pd1-x catalysts over a temperature range of 333-593 K and a range of inlet H2 and D2 partial pressures. X-ray photoelectron spectroscopy (XPS) was used to characterize the CSAF by determining the local surface compositions and the valence band electronic structure at each composition. The valence band photoemission spectra showed that the average energy of the valence band, ε̅v, shifts linearly with composition from -6.2 eV for pure Ag to -3.4 eV for pure Pd. At all reaction conditions, the H2-D2 exchange activity was found to be highest on pure Pd and gradually decreased as the alloy was diluted with Ag until no activity was observed for compositions with x Pd < 0.58. Measured H2-D2 exchange rates across the CSAF were fit using the Dual Subsurface Hydrogen (2H') mechanism to extract estimates for the activation energy barriers to dissociative adsorption, ΔE ads ‡, associative desorption, ΔE des ‡, and the surface-to-subsurface diffusion energy, ΔE ss, as a function of alloy composition, x Pd. The 2H' mechanism predicts ΔE ads ‡ = 0-10 kJ/mol, ΔE des ‡ = 30-65 kJ/mol, and ΔE ss = 20-30 kJ/mol for all alloy compositions with x Pd ≥ 0.64, including for the pure Pd catalyst (i.e., x Pd = 1). For these Pd-rich catalysts, ΔE des ‡ and ΔE ss appeared to increase by ∼5 kJ/mol with decreasing x Pd. However, due to the coupling of kinetic parameters in the 2H' mechanism, we are unable to exclude the possibility that the kinetic parameters predicted when x Pd ≥ 0.64 are identical to those predicted for pure Pd. This suggests that H2-D2 exchange occurs only on bulk-like Pd domains, presumably due to the strong interactions between H2 and Pd. In this case, the decrease in catalytic activity with decreasing x Pd can be explained by a reduction in the availability of surface Pd at high Ag compositions.

Novel multineedle-to-cylinder plasma coupled with bimetallic catalysts for efficient removal of sulfides and ammonia in odor gases

Dielectric barrier discharge (DBD) plasma is a promising technology for treating odor gases. This study developed an innovative multineedle-to-cylinder (MC) configuration DBD plasma reactor and investigated its synergistic effect with bimetallic catalysts. The results demonstrated that MC-DBD plasma achieved complete elimination of ammonia and organic sulfides, while the removal efficiencies of inorganic H2S and CS2 reached 44.0 % and 53.0 % respectively. Compared with conventional plasma, the specific energy input (SEI) of MC-DBD was significantly reduced to 4.44 J/L. Furthermore, with the incorporation of Mn-Ce/ZSM-5 catalyst, optimal removal efficiencies of H2S and CS2 were significantly improved to 82.6 % and 90.7 %, and the SEI was reduced by 18 %. The electrical performance revealed that the low energy consumption was mainly attributed to stable fast-pulse micro-discharge channels and significantly enhanced inhomogeneous electric fields achieved by the filament discharge mode. Catalyst characterization (X-ray photoelectron spectroscopy and O2-temperature programming desorption) confirmed that surface catalytic reaction mainly follows the Mars-van Krevelen mechanism, where increased lattice oxygen content and the electron transfer between Mn and Ce play crucial roles in enhancing malodor degradation performance. This work proposes an efficient solution for degrading mixed malodors and provides an experimental and theoretical basis for optimizing plasma structure as well as researching treatment of mixed pollutants.

Entropy of the surface catalytic reaction: Expansion of the advanced H2S paradigm to novel catalytic systems

Entropy of the surface catalytic reaction: Expansion of the advanced H2S paradigm to novel catalytic systems

Electronic Decoupling and Hole-Doping of Graphene Nanoribbons on Metal Substrates by Chloride Intercalation.

Atomically precise graphene nanoribbons (GNRs) have a wide range of electronic properties that depend sensitively on their chemical structure. Several types of GNRs have been synthesized on metal surfaces through selective surface-catalyzed reactions. The resulting GNRs are adsorbed on the metal surface, which may lead to hybridization between the GNR orbitals and those of the substrate. This makes investigation of the intrinsic electronic properties of GNRs more difficult and also rules out capacitive gating. Here, we demonstrate the formation of a dielectric gold chloride adlayer that can intercalate underneath GNRs on the Au(111) surface. The intercalated gold chloride adlayer electronically decouples the GNRs from the metal and leads to a substantial hole-doping of the GNRs. Our results introduce an easily accessible tool in the in situ characterization of GNRs grown on Au(111) that allows for exploration of their electronic properties in a heavily hole-doped regime.

Unveiling the Role of Sulfur Vacancies in Enhanced Photocatalytic Activity of Hybrids Photocatalysts.

Photocatalysis represents a sustainable strategy for addressing energy shortages and global warming. The main challenges in the photocatalytic process include limited light absorption, rapid recombination of photo-induced carriers, and poor surface catalytic activity for reactant molecules. Defect engineering in photocatalysts has been proven to be an efficient approach for improving solar-to-chemical energy conversion. Sulfur vacancies can adjust the electron structure, act as electron reservoirs, and provide abundant adsorption and activate sites, leading to enhanced photocatalytic activity. In this work, we aim to elucidate the role of sulfur vacancies in photocatalytic reactions and provide valuable insights for engineering high-efficiency photocatalysts with abundant sulfur vacancies in the future. First, we delve into the fundamental understanding of photocatalysis. Subsequently, various strategies for fabricating sulfur vacancies in photocatalysts are summarized, along with the corresponding characterization techniques. More importantly, the enhanced photocatalytic mechanism, focusing on three key factors, including electron structure, charge transfer, and the surface catalytic reaction, is discussed in detail. Finally, the future opportunities and challenges in sulfur vacancy engineering for photocatalysis are identified.

In situ formation of inhibitor species through catalytic surface reactions during area-selective atomic layer deposition of TaN.

Small molecule inhibitors (SMIs) have been gaining attention in the field of area-selective atomic layer deposition (ALD) because they can be applied in the vapor-phase. A major challenge for SMIs is that vapor-phase application leads to a disordered inhibitor layer with lower coverage as compared to self-assembled monolayers, SAMs. A lower coverage of SMIs makes achieving high selectivity for area-selective ALD more challenging. To overcome this challenge, mechanistic understanding is required for the formation of SMI layers and the resulting precursor blocking. In this study, reflection adsorption infrared spectroscopy measurements are used to investigate the performance of aniline as an SMI. Our results show that aniline undergoes catalytic surface reactions, such as hydrogenolysis, on a Ru non-growth area at substrate temperatures above 250 °C. At these temperatures, a greatly improved selectivity is observed for area-selective TaN ALD using aniline as an inhibitor. The results suggest that catalytic surface reactions of the SMI play an important role in improving precursor blocking, likely through the formation of a more carbon-rich inhibitor layer. More prominently, catalytic surface reactions can provide a new strategy for forming inhibitor layers that are otherwise very challenging or impossible to form directly through vapor-phase application.

A Review of the Effect of Defect Modulation on the Photocatalytic Reduction Performance of Carbon Dioxide.

Constructive defect engineering has emerged as a prominent method for enhancing the performance of photocatalysts. The mechanisms of the influence of defect types, concentrations, and distributions on the efficiency, selectivity, and stability of CO2 reduction were revealed for this paper by analyzing the effects of different types of defects (e.g., metallic defects, non-metallic defects, and composite defects) on the performance of photocatalysts. There are three fundamental steps in defect engineering techniques to promote photocatalysis, namely, light absorption, charge transfer and separation, and surface-catalyzed reactions. Defect engineering has demonstrated significant potential in recent studies, particularly in enhancing the light-harvesting, charge separation, and adsorption properties of semiconductor photocatalysts for reducing processes like carbon dioxide reduction. Furthermore, this paper discusses the optimization method used in defect modulation strategy to offer theoretical guidance and an experimental foundation for designing and preparing efficient and stable photocatalysts.