Carrier Recombination Research Articles

Efficient α–Fe2O3@NiO nanocomposites as a photocatalyst for the treatment of hazardous Rose Bengal dye

This work aims to determine the structural, optical, and magnetic characteristics of α-Fe2O3/NiO nanocomposites and their application in the treatment of water contaminated by RB dyes. Utilizing the cost-effective chemical co-precipitation method, nanocomposites with weight ratios of α-Fe2O3: NiO (1:1, 2:1, and 1:2) were produced. The XRD pattern was used to identify the synthesized materials that contained NiO and α-Fe2O3 phases. Lattice flaws and oxygen vacancies were found using XPS spectra. Magnetic experiments reveal that α-Fe2O3@NiO (1:2) has strongest magnetic character among all synthesized materials, with a maximum magnetization of 35.56 emu/g. The improved photocatalytic activity of α-Fe2O3/NiO (2:1) nanocomposites achieved a maximum of approximately 94 % degradation of Rose Bengal dye in 90 min. The increased photocatalytic activity can be attributed to synergistic contribution of α-Fe2O3 and NiO, which inhibits photo-generated charge carrier recombination and formation of highly active radical species (OH• radicals, and O2• radicals).

Over 10% Efficiency Pure Sulfide Kesterite Solar Cells on Transparent Electrode with Cd-Ag Co-Alloying.

The environmentally friendly elements composed of high bandgap pure sulfide Cu2ZnSnS4 (CZTS) semiconductor has broad prospects for building integrated photovoltaic, double-sided, and semi-transparent solar cells when fabricated on transparent substrates. The key issues limiting the performance of CZTS solar cells are poor absorber quality and unfavorable band energy alignment causing serious charge carrier recombination. Here, thefabrication of CZTS solar cells are reported on fluorine-doped tin oxide (FTO) substrates from dimethyl sulfoxide solution and the effects of the Cd and Ag alloying on device performance. Characterizations show that Cd alloying greatly decreases defect concentration and converts Cliff-type band alignment to favorable Spike-type, leading to greatly improved current density. Further, Ag alloying eliminates near-horizontal grain boundaries and passivates defects in both bulk and heterojunction interface, resulting in a champion device with a power conversion efficiency of 10.3%, the highest efficiency pure sulfide CZTS solar cell on FTO substrate. The results demonstrate the great application potential of pure sulfide kesterite solar cells.

Enhanced catalytic activity of modified g-C3N4 heterojunction for photocatalytic degradation of methylene blue from wastewater

Rapid recombination of photoinduced charge carriers and poor photocatalytic degradation performance greatly hinder the large-scale application of g-C3N4 photocatalysis. Therefore, the g-C3N4 is modified by BiPO4 to overcome its poor photocatalytic performance, which is investigated by methylene blue (MB) removal. The S scheme heterojunction is constructed by modifying g-C3N4 with BiPO4, which can effectively preserve the redox activities of holes and electrons on VB and CB, exhibiting good photocatalytic activity. Therefore, the modified g-C3N4 exhibits excellent photocatalytic activity with efficient separation of the photoelectron-hole, compared to pure g-C3N4 and BiPO4. The modified g-C3N4 exhibits large MB degradation removal of 96.7 %, which is significantly larger than the pure g-C3N4 (46.3 %) and BiPO4 (3.3 %) owe to synergy, respectively. The photodegradation rate constant of the modified g-C3N4 is 4.8 and 43 times larger than that of the pure g-C3N4 and BiPO4, respectively. The modified g-C3N4 still has large MB removal of 92.9 % after 5 cycles, indicating excellent stability and recyclability. The fractal density calculation of the modified g-C3N4 is investigated combined with LUMO and HOMO analysis. The MB photocatalytic degradation process follows the S scheme charge transfer mechanism, based on degradation mechanism analysis combined with semiconductor energy band and density functional theory calculation analysis. The MB photocatalytic degradation path is systemically analyzed based on MS-UPLC result analysis, which indicates that MB is finally decomposed into CO2 and H2O, achieving the degradation of MB.

Highly active Cu2O/CoCo-PBA S-scheme heterojunction for enhanced visible-light-driven hydrogen evolution

Prussian blue analogues is a unique class of organic-inorganic hybrid materials that have garnered significant attention in the field of photocatalysis due to their large specific surface area and abundant active sites. However, their potential is limited by the challenge of photogenerated charge carrier recombination. To address this issue, we successfully synthesized a tightly coupled Cu2O/CoCo-PBA S-scheme heterojunction catalyst using ultrasound-assisted and thermal treatment methods, aiming to reduce the recombination of photogenerated charge carriers. In this system, CoCo-PBA serves as the electron donor, while Cu2O acts as the electron acceptor. The closely coupled interface between these materials shortens the electron transfer distance. Under 10 W white light irradiation, the Cu2O/CoCo-PBA composite photocatalyst demonstrated remarkable hydrogen evolution activity, with a hydrogen production rate of 5.98 mmol⋅g⁻¹⋅h⁻¹, which is 6.4 times that of CoCo-PBA alone. This S-scheme heterojunction strategy lays the groundwork for the design and large-scale application of highly active visible-light-driven photocatalysts.

Gradient Thermal Annealing Assisted Perovskite Film Crystallization Regulation for Efficient and Stable Photovoltaic-Photodetection Bifunctional Device.

Perovskite crystallization regulation is essential to obtain excellent film optoelectronic properties and device performances. However, rapid crystallization during annealing always results in poor perovskite film and easy formation of trap, thereby greatly restricting device performance due to severe non-radiative recombination. Here, an easy and reproducible gradient thermal annealing (GTA) approach is used to regulate the perovskite crystallization. Through a low-temperature initial annealing of GTA, the solvent evaporation is slowed down, thus extending nucleation time and providing a buffer for the rapid crystallization of perovskite grains in the subsequent high-temperature stage. As a result, completely converted and highly crystalline perovskite is obtained with 1.6 times larger grain size, reduced trap density and suppressed non-radiative recombination of photo-generated carriers. The film crystallinity is also enhanced with more advantageous (100) and (111) lattice facets which are favorable for carrier transport. Consequently, the perovskite photodetectors exhibit a large linear dynamic range of 174dB and an excellent response even under ultra-weak light of 303 pW. Meanwhile, perovskite solar cells achieved increased PCE and maintained 85% of original efficiency after heating at 65°C for nearly 1000 h under unencapsulated conditions. To the knowledge, this represents the best performance reported for a perovskite photovoltaic-photodetection bifunctional device.

Functional coupling hole transport and extraction units over BiVO4 for efficient solar-to-hydrogen conversion

Photoelectrochemical (PEC) water splitting based on BiVO4 nanostructures is largely limited by the fast recombination of charge carriers and the low oxygen evolution reaction (OER) kinetics. To enhance PEC performance of BiVO4, combining hole transport units and hole extraction units is a simple and effective methods. In this work, Co3O4 and NiFe layered double hydroxide (NiFe-LDH) were coupled to promote bulk-phase charge separation and solid–liquid interface transfer, which accelerated OER kinetics on surface of target photoanodes. Moreover, p-n heterojunction between BiVO4 and Co3O4 suppressed charge recombination and promoted charge transfer, resulting in an effectively enhanced photocurrent density and applied bias photon to current efficiency (ABPE). To facilitate involvement of photogenerated holes in OER, BiVO4/Co3O4 electrodes are coated with NiFe-LDH as a hole extraction layer using a straightforward chemical bath deposition (CBD) technique. Successful fabrication of NiFe-LDH with rich oxygen vacancies significantly improves transport of charge carriers and provides many activity sites on the electrode surface. The optimized BiVO4/Co3O4/NiFe-LDH photoanode displayed a photocurrent density of 5.41 mA cm−2 at 1.23 VRHE with an ABPE of 1.08 % at 0.86 VRHE under light. These values are approximately 4.66 and 8.30 times higher than those of BiVO4 photoanodes. This study presents a powerful approach to enhance charge separation and transport in BiVO4-based photoanodes by functionally coupling hole transport and extraction units, thereby enabling efficient solar-to-hydrogen conversion.

A strategy for achieving high-performance single layer polymer photodetectors through dark current reduction using PMMA additives

Suppressing dark current density is crucial for optimizing the performance of organic photodetectors (PDs), particularly in terms of detectivity (D∗) and linear dynamic range (LDR). Organic PDs often utilize the bulk heterojunction structure of organic solar cells to significantly increase photocurrent. However, unlike solar cells, which are unaffected by dark current, photodetectors' performance is substantially limited by it. The interconnected network of bulk heterojunctions leads to a noticeable increase in dark current, thus degrading device performance. Typically, reducing dark current involves adding a modification layer or using multilayer planar heterojunctions, which effectively reduce dark current but often delay response speed and complicate manufacturing. This study presents an alternative approach by incorporating a small concentration of PMMA into single-layer polymer photodetectors, significantly reducing dark current without affecting photocurrent. For this single-layer polymer PD, an ultra-low dark current density of 1.25 × 10−8 A/cm2, a high Dsh∗ of 2.74 × 1012 Jones, an LDR of 120.5 dB, and a fast response time with 1.6 μs were achieved. The capacitance-voltage (C-V), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and atomic force microscopy (AFM) measurements revealed that the PMMA additive reduces internal defects, increases bulk resistance, optimizes phase separation, and enhances carrier transport efficiency. The improved device performances are attributed to a more efficient vertical arrangement of the donor-acceptor interface and carrier channels, thus reducing carrier recombination loss. These findings offer a new direction for fabricating high-performance single-layer photodetectors.

27.09%-efficiency silicon heterojunction back contact solar cell and going beyond

Crystalline-silicon heterojunction back contact solar cells represent the forefront of photovoltaic technology, but encounter significant challenges in managing charge carrier recombination and transport to achieve high efficiency. In this study, we produced highly efficient heterojunction back contact solar cells with a certified efficiency of 27.09% using a laser patterning technique. Our findings indicate that recombination losses primarily arise from the hole-selective contact region and polarity boundaries. We propose solutions to these issues and establish a clear relationship between contact resistivity, series resistance, and the design of the rear-side pattern. Furthermore, we demonstrate that the wafer edge becomes the main channel for current density loss caused by carrier recombination once electrical shading around the electron-selective contact region is mitigated. With the advanced nanocrystalline passivating contact, wafer edge passivation technologies and meticulous optimization of front anti-reflection coating and rear reflector, achieving efficiencies as high as 27.7% is feasible.

Interface induced photoluminescence enhancement from heterojunction BaMoO4/HEAs phosphors: Experiment, theory and anti-counterfeiting application

The BaMoO4/FeCoNiCrMo (BMO/HEA(Mo)), BMO/FeCoNiCrTi (HEA(Ti)) and BMO/FeCoNiCrTiAl (HEA(Al)) phosphors were synthesized by an integrated technology. The structural characterization showed that except the main lattice phase, only the characteristic peak of high-entropy alloys (HEAs) appeared in BMO/HEAs phosphors and the existence of lattice distortion for [MoO4]2- in BMO. The microstructure analysis confirmed that there is a special interface contact between BMO and HEAs, which makes the metal in HEAs easy to have a certain connection with BMO, which causes the lattice distortion of [MoO4]2- to intensify, thus accelerating the recombination rate of charge carriers in BMO/HEAs phosphors. The BMO/HEAs phosphors have a strong emission peak at 445 nm under the excitation wavelength of 285 nm. Theoretical calculations and experiments confirmed that the luminescence of BMO/HEAs phosphor is caused by the lattice distortion of [MoO4]2-, the interface defect of BMO/HEAs and the recombination of charge carriers. The Mo in HEA(Mo) can accelerate the recombination rate of charge carriers between BMO and HEAs, thus enhancing the luminescence performance of BMO/HEA(Mo) phosphor and exhibit dynamic fluorescence anti-counterfeiting applications. However, the Ti in HEA(Ti) and Al in HEA(Al) can easily separate the charge carriers between BMO and HEAs, thus reducing the luminescence of BMO/HEA(Ti) and BMO/HEA(Al) phosphors.

Overall water splitting of type-I vdW heterojunction ZnS/Ga2SSe

In the domain of photocatalysis, type I heterojunctions have received limited attention, and the quest for effective type I photocatalysts persists. This study introduces a novel type I heterostructure, ZnS/Ga2SSe, and gives a systematic investigation of its electronic properties, optical properties, and photocatalytic performance by DFT calculations. Electronic properties show that ZnS/Ga2SSe system has a type I band alignment with a 2.26 eV band gap. Different from traditional type I heterostructure, ZnS/Ga2SSe has an obvious interfacial electric field and a potential barrier, which promotes spatial charge separation and addresses the drawback of easy recombination of photo-generated carriers in traditional type I heterojunctions. The calculated results of Gibbs free energy show that under the 3.3 eV external potential and pH = 14, water splitting reaction can be achieved spontaneously. Moreover, the heterojunction shows good optical absorption in visible regions and 22.28 % STH efficiency which is higher than the reported type I photocatalysts. The biaxial strain can modulate the electronic structure and maintain type I alignment. Tensile can reduce the bandgap and enhance optical absorption, while compression is the opposite. Under 4 % tensile, STH efficiency can reach 40.3 %, while −4 % compression it will decrease to 10.3 %. These conclusions underline the potential of the ZnS/Ga2SSe heterojunction as a promising photocatalytic material candidate for water splitting and type I heterojunctions is worth exploring as photocatalysis.

Synergistic impact of lanthanum and cerium co-doping ZnO for improved photocatalytic rhodamine B degradation efficiency under UV light

In this study, the influence of different La and Ce co-doping amounts on the structural, morphological, optical, and photodegradation properties of ZnO nanostructures was evaluated. Zn1–2xLaxCexO nanoparticles (NPs) were prepared using sol-gel auto-ignition process, where x = 0.00 (pure ZnO), 0.01 (LC1), 0.03 (LC3), and 0.05 (LC5). The X-ray diffraction (XRD) and Raman results revealed that the prepared ZnO NPs crystallize in the hexagonal wurtzite structure. The size of crystallites is affected by the increment of La and Ce and it decreased from 24.29 nm to 10.40 nm with the increase in the concentration of La and Ce. Transmission electron microscopy (TEM) showed that the samples exhibit an irregular distribution of NPs with a dominant spherical shape morphology. The simultaneous incorporation of La and Ce in ZnO NPs led to a slight variation in the absorption edge and a slight shift in the values of the band gap energy from 3.20 to 3.24 eV. Furthermore, a reduction in the recombination rate of photogenerated charge carriers and the creation of fewer additional defects upon the appropriate insertion of Ce and La ions are highlighted by the analysis of photoluminescence spectra, Nyquist plots, and transient photocurrent measurements. The photocatalytic activity of samples was evaluated against rhodamine B organic dye under UV light irradiation. The analysis showed that LC1 sample exhibited superior photocatalytic performance with 99.1 % degradation efficiency and a degradation rate constant of 0.0762 min-1. This enhancement has been ascribed to the surface defects and the optimized crystallite size achieved, which help to generate reactive entities such as •OH and O2•− in addition to the great role of holes (h+) and impede the recombination of charge carriers e-/h+.

Black Phosphorus for Mid-Infrared Optoelectronics: Photophysics, Scalable Processing, and Device Applications.

High efficiency mid-infrared (λ = 3-8 μm) light emitters and photodetectors are pivotal for advancing next-generation optoelectronics. However, narrow-bandgap semiconductors face fundamental challenges such as pronounced nonradiative carrier recombination and thermally generated noise, which impede device performance. Recently, two-dimensional layered black phosphorus (BP) and its alloys have attracted substantial interest for mid-infrared device applications, demonstrating superior performance relative to conventional III-V and II-VI semiconductors with similar bandgaps. In this review, we discuss the optical properties of BP, contrasting these with those of covalent compounds. Owing to its inherently self-terminated surface structure and reduced nonradiative recombination, BP exhibits high performance in light emission and photodetection at room temperature. Furthermore, this review highlights recent advances in the large-area processing of BP thin films, paving the way for practical device applications and integration. Finally, we explore ongoing challenges and emerging opportunities in the utilization of BP for functional mid-infrared devices.

Room-Temperature Ripening Enabled by Hygroscopic Salts for Hole-conductor-Free Printable Perovskite Solar Cells with Efficiency Over 20 .

Solution-processed perovskite films generally possess small grain sizes and high density of grain boundaries, which intensify non-radiative recombination of carriers and limit the power conversion efficiency (PCE) of solar cells. In this study, we report the room-temperature ripening enabled by the synergy of hygroscopic salts and moisture in air for efficient hole-conductor-free printable mesoscopic perovskite solar cells (p-MPSCs). Treating perovskite films with proper hygroscopic salts in damp air induces obvious secondary recrystallization, which coarsens the grains size from hundreds of nanometers to several micrometers. It's proposed that the hygroscopic salt at grain boundaries could absorb moisture and form a complex which could not only serve as mass transfer channel but also assist in the dissolution of perovskite grains. This activates mass transfer between small grains and large grains since they possess different solubilities, and thus ripens the perovskite film. Consequently, p-MPSCs treated with the hygroscopic salt of NH4SCN show an improved power conversion efficiency of 20.13 % from 17.94 %, and maintain >98 % of the initial efficiency under maximum power point tracking at 55±5 °C for 350 hours.

Internal Capsulation Via Self-Cross-linking and π-Effects Achieves Highly Stable Perovskite Solar Cells.

Pursuing high stability becomes the core challenge in realizing the widespread application of perovskite solar cells (PerSCs). Here, a practical internal-capsulation strategy is proposed by introducing cross-linkable methacrylate analogs upon the perovskite layer, hindering ion migration and preventing lead leakage to achieve stable PerSCs. Butyl methacrylate (UMA) and benzyl methacrylate (BMA) can chemically interact with the perovskite layer, especially for the BMA dimer with significant π-interactions among the hanging benzene rings. Such configuration facilitated more compact coordination, thereby restoring the Fermi level of perovskite to a defect-free state and reducing carrier recombination losses. Moreover, by integrating the self-cross-linking and intermolecular π-effect, the application of BMA upgraded the internal capsulation from linear protection to a compact mesh-like scale. Consequently, the application of BMA not only boosted the efficiency to 25.31% but also greatly enhanced the stability of the perovskite layer, especially for water resistance and preventing lead linkage. The internal capsulation strategy upgrading from linear to mesh-like marked an innovative direction in protecting the perovskite layer, paving the way for more sustainable PerSCs in further application.

Dynamics of Nonlinear Optical Losses in Silicon‐Rich Nitride Nano‐Waveguides

AbstractFree carrier absorption (FCA) is established to be the cause of nonlinear losses in plasma‐enhanced chemical vapor deposition (PECVD) silicon‐rich nitride (SRN) waveguides. To validate this hypothesis, a photo‐induced current is measured in SRN thin films with refractive indices varying between 2.5 and 3.15 when a C‐band laser light is illuminating the SRN films at various powers, indicating the generation of free carriers. Furthermore, nonlinear loss dynamics is, for the first time, measured and characterized in detail in SRN waveguides by utilizing high peak power C‐band complex shape optical pulses for estimation of free carrier generation (FCG) and free carrier recombination (FCR) lifetimes and their dynamics. Both FCG and FCR are found to decrease with an increase in the refractive index of SRN, and, specifically, the FCR lifetimes are found (92 ± 7) ns, (39 ± 3) ns, and (31 ± 2) ns for the SRN indices of 2.7, 3, and 3.15, respectively. Lastly, nonlinear losses in high refractive index SRN waveguides are demonstrated to be minimized and altogether avoided when the pulse duration reduced below the free carrier generation lifetime, thus providing a way of taking a full advantage of the large inherent SRN nonlinear properties.

Performance Enhancement of Hole Transport Layer-Free Carbon-Based CsPbIBr2 Solar Cells through the Application of Perovskite Quantum Dots.

CsPbIBr2, with its suitable bandgap, shows great potential as the top cell in tandem solar cells. Nonetheless, its further development is hindered by a high defect density, severe carrier recombination, and poor stability. In this study, CsPbI1.5Br1.5 quantum dots were utilized as an additive in the ethyl acetate anti-solvent, while a layer of CsPbBr3 QDs was introduced between the ETL and the CsPbIBr2 light-harvester film. The combined effect of these two QDs enhanced the nucleation, crystallization, and growth of CsPbIBr2 perovskite, yielding high-quality films characterized by an enlarged crystal size, reduced grain boundaries, and smooth surfaces. And a wider absorption range and better energy band alignment were achieved owing to the nano-size effect of QDs. These improvements led to a decreased defect density and the suppression of non-radiative recombination. Additionally, the presence of long-chain organic molecules in the QD solution promoted the formation of a hydrophobic surface, significantly enhancing the long-term stability of CsPbIBr2 PSCs. Consequently, the devices achieved a PCE of 9.20% and maintained an initial efficiency of 85% after 60 days of storage in air. Thus, this strategy proves to be an effective approach for the preparation of efficient and stable CsPbIBr2 PSCs.

Influence of sulfurization process in tin sulfide and sulfur mixed vapors on the morphology of Cu2SnS3 thin films

Abstract Cu2SnS3 (CTS) is expected to be an absorber material for next-generation solar cells because it is composed of nontoxic, low-cost elements and has an absorption coefficient of >104 cm−1. In this study, the effects of sulfurization in tin sulfide (Sn x S y ) and S mixed vapors on various properties of CTS were investigated by using a 3-zone tube furnace to suppress carrier recombination at the grain boundaries and control the composition of the CTS. The CTS deposited via sulfurization in S vapor only (1-zone CTS) contained different monoclinic and tetragonal CTS structures. The grain size of the CTS thin films deposited via sulfurization in Sn x S y and S mixed vapors was not increased. On the other hand, crystal structure analysis revealed that the CTS had grown to single-phase monoclinic CTS. The results suggest that precipitation in Sn x S y and S mixed vapors contributes to the growth of monoclinic CTS with suitable power-generation characteristics. This finding is important for realizing high-efficiency CTS-based solar cells.

The key role of anti-solvent temperature in quantum dot/perovskite core-shell nanowire array solar cells

Combining perovskite with infrared quantum dots to construct a core-shell nanostructure nanowire array solar cell can increase the light absorption range and enhance the light absorption and carrier transport efficiency of the solar cell. However, the preparation of a perovskite absorber layer on a nanowire array with quantum dots often presents issues such as high roughness and a large number of lattice defects, which have a negative impact on the photovoltaic performance. The anti-solvent method is a commonly used technique to improve the quality of perovskite. The temperature variation of the anti-solvent can change solubility, and influence the reaction rate and crystal formation process of perovskite, thus affecting its photovoltaic performance. In this study, the quality of perovskite in the core-shell nanostructure nanowire array was improved by controlling the temperature of the anti-solvent (toluene). Experimental results show that as the temperature of toluene increases, the photovoltaic performance is gradually improved. When the toluene temperature was maintained at 75 °C, the device exhibited significantly improved photovoltaic performance with an efficiency of 12.64 %, surpassing the efficiency obtained without any anti-solvent modification. As the temperature of the anti-solvent increases, the absorption of visible and near-infrared light spectrum by the nanowire arrays is enhanced, which promotes the efficient generation of photo-generated carriers. Furthermore, defects in the nanowire arrays gradually decrease, leading to a reduction in carrier recombination. These findings provide valuable insights for advancing core-shell nanostructure nanowire array solar cells.

Carrier Dynamics and Recombination Pathways in Ag-In-Zn-S Quantum Dots.

Strong tolerance to off-stoichiometry of group I-III-VI semiconductors in their nanocrystal form allows fabrication of multinary, alloyed structures of desired properties. In particular, alloyed Cu-In-Zn-S and Ag-In-Zn-S quantum dots (QDs) have recently emerged as efficient fluorophors, in which tailoring the composition allows tuning the optical properties, and achieving photoluminescence (PL) quantum yields approaching unity. However, poor understanding of the carrier recombination mechanism in these materials limits their further development. In this work, by studying transient absorption and temperature dependent PL on bare QDs and QDs conjugated with electron scavenger molecules, we obtain a detailed picture of carrier dynamics. Our results challenge the prevailing assumption that the PL is due to a donor-acceptor-pair transition. We show that the PL occurs as a result of a recombination of a delocalized electron with a localized hole.

Rod-shaped Cd0.8Mn0.2S and Co3O4 quantum dots construct S-scheme heterojunction for photocatalytic hydrogen evolution

Photocatalytic water splitting for hydrogen production is one of the key pathways to achieving a zero-carbon economy. Cd0.8Mn0.2S has significant potential for photocatalytic hydrogen evolution, but it faces serious challenges due to the recombination of photogenerated charge carriers. To address this issue, we successfully coupled Co3O4 QDs onto Cd0.8Mn0.2S nanorods via ultrasonic self-assembly, constructing a S-scheme heterojunction to reduce charge carrier recombination rates. In this configuration, Co3O4 QDs serves as the electron donor, while Cd0.8Mn0.2S act as the electron acceptor. The Cd0.8Mn0.2S/Co3O4 QDs structure creates a closely spaced interface, providing the shortest possible path for electron transfer. Under 10 W white light irradiation, the Cd0.8Mn0.2S/Co3O4 QDs composite photocatalyst exhibited remarkable hydrogen evolution activity, achieving a hydrogen production rate of 33.39 mmol⋅g⁻¹⋅h⁻¹. This S-scheme heterojunction strategy lays the foundation for the structural design of highly active visible-light photocatalysts.