Hierarchical Heterostructures Research Articles

Engineering hierarchical heterostructure material based on multiwalled carbon nanotubes/SnO2 nanorod-flowers for high-efficient ammonia detection

The rational manufacturing of multi-component materials with rich heterostructure is emerging as a possible strategy to develop improved carbon nanotube-based gas sensors. Herein, hierarchical heterostructure of multiwalled carbon nanotubes/SnO2 nanorod-flowers (HMCNS) was synthesized by a facile water-bathing combined hydrothermal approach for highly sensitive ammonia detection. Exploration in the microstructure reveals that hierarchical flowers-like SnO2 consisted of nanorods demonstrates a hollow geometry for wrapping multiwalled carbon nanotubes, featuring a unique three-dimensional (3D) hierarchical architecture. Gas sensor based on SnO2@4.5%CNTs hierarchical heterostructure exhibits highly enhanced ammonia-sensing performances, including ultra-high response of 1650 toward 20 ppm ammonia, good selectivity, 250 ppb level detection, and superior long-term stability. The improvement in ammonia sensing capability could be attributed to the peculiar hierarchical architecture and the creation of Mott-Schottky heterostructure which has been strongly validated by electrochemical research. This work will provide a concise and effective avenue to construct hierarchical composite with Mott-Schottky heterostructure for high-performance ammonia gas sensor.

Well-Dispersed CoNiO2 Nanosheet/CoNi Nanocrystal Arrays Anchored onto Monolayer MXene for Superior Electromagnetic Absorption at Low Frequencies

Developing microwave absorbers with superior low-frequency electromagnetic wave absorption properties is one of the foremost important factors driving the boom in 5G technology development. In this study, via a simple hydrothermal and pyrolysis strategy, randomly interleaved CoNiO2 nanosheets and uniformly ultrafine CoNi nanocrystals are anchored onto both sides of a single-layered MXene. The absorption mechanism demonstrated that the hierarchical heterostructure prevents the aggregation of MXene nanoflakes and magnetic crystallites. In addition, the introduction of the double-magnetic phase of CoNiO2/CoNi arrays can not only enhance the magnetic loss capacity but also generate larger void spaces and abundant heterogeneous interfaces, collectively promoting impedance-matching and furthering microwave attenuation capabilities at a low frequency. Hence, the reflection loss of the optimal absorber (M–MCNO) is −45.33 dB at 3.24 GHz, which corresponds to a matching thickness of 5.0 mm. Moreover, its EAB can entirely cover the S-band and C-band by tailoring the matching thickness from 2 to 7 mm. Satellite radar cross-section (RCS) simulations demonstrated that the M–MCNO can reduce the RCS value to below −10 dB m2 over a multi-angle range. Thus, the proposed hybrid absorber is of great significance for the development of magnetized MXene composites with superior low-frequency microwave absorption properties.

Self-assembly of NiFe-LDH@Ni3S2 sub-nanosheets catalyst for overall water splitting

The development of water splitting catalysts for generating high-purity hydrogen in large-scale is still facing challenges in terms of improving efficiency and stability. Herein, Ni3S2-coated NiFe layered double hydroxides sub-nanosheets with a hierarchical heterostructure (NiFe-LDH@Ni3S2) were prepared on nickel foam (NF) by a strategy of continuous hydrothermal synthesis. The introduction of S2− broke the hydrogen bonds between NiFe-LDH layers and separated into sub-nanosheets with a thickness of only about 1 nm, which enlarged the active areas of NiFe-LDH@Ni3S2/NF by a factor of 5.7. The coexisting charge channels Ni-O-Ni and Ni-S-Ni in the material enhanced the electrochemical activity, resulting in the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) overpotentials as low as 179 mV and 116 mV at 10 mA cm−2 in 1.0 M KOH. Moreover, after a 50-hour chronopotentiometry test at 50 mA cm−2, the overpotential for OER and HER decreased only 0.013 V and 0.059 V, respectively. Furthermore, under the conditions of simulating industrial hydrogen production with an electrolyte of 6.0 M KOH and a temperature of 75 °C, after a 140-hour test for durability, the current density decreased only 0.75% at the cell voltage of 1.70 V.

High Energy Storage Performance in BiFeO3-Based Lead-Free High-Entropy Ferroelectrics.

Dielectric capacitors are widely used in advanced electrical and electronic systems due to the rapid charge/discharge rates and high power density. High comprehensive energy storage properties are the ultimate ambition in the field of application achievements. Here, the high-entropy strategy is proposed to design and fabricate single-phase homogeneous (Bi0.5Ba0.1Sr0.1Ca0.2Na0.1)(Fe0.5Ti0.3Zr0.1Nb0.1)O3 ceramic, the hierarchical heterostructure including rhombohedral-tetragonal multiphase nanoclusters and locally disordered oxygen octahedral tilt can lead to the increased dielectric relaxation, diffused phase transition, diverse local polarization configurations, grain refinement, ultrasmall polar nanoregions, large random field, delayed polarization saturation and improved breakdown field. Accordingly, a giant Wrec ≈13.3 J cm-3 and a high η ≈78% at 66.4kV mm-1 can be simultaneously achieved in the lead-free high-entropy BiFeO3-based ceramic, showing an obvious advantage in overall energy-storage properties over BiFeO3-based lead-free ceramics. Moreover, an ultrafast discharge rate (t0.9 = 18ns) can be achieved at room temperature, concomitant with favorable temperature stability in the range of 20-160 °C, due to the enhanced diffuse phase transition and fast polarization response. This work provides a feasible pathway to design and generate dielectric materials exhibiting high comprehensive energy-storage performance.

In-situ growth of vertically stacked 2D SnS2/SnS heterostructure for highly sensitive and rapid room temperature NO2 gas sensor

Construction of 2D heterostructure is a potential strategy to improve the sensing performance of 2D layered materials owing to the high-quality of heterointerfaces. This attributed to the remarkable electronic band alignment between the constituent materials and their distinctive characteristics. Woefully, very limited attempts have been taken to investigate the effect of 2D heterointerface for gas sensing applications. Here, the SnS2/SnS heterostructure is fabricated on a SiO2/Si substrate using a single-step atmospheric chemical vapor deposition technique for room temperature NO2 sensing. The heterostructure has imparted a 1.3 times enhancement in response (S(%)), with ultra-fast response (τres) and recovery time (τrec) of 32s and 382s, towards 40 ppm of NO2 at 30 °C. Moreover, the impact of humidity on the sensing performance of SnS2/SnS has also been studied, confirming its negligible effect on relative humidity. Additionally, it also demonstrates a remarkable stability of 93% over a period of 40 days. Besides, due to strong adsorption energy of SnS2 (1914 meV) and SnS (600meV) towards NO2 endorses the reaction kinetic parameters validated by the gas adsorption/desorption isotherm analysis of heterostructure. The substantial interface contacts between the SnS2/SnS heterostructure facilities the fermi-level mediated charge transfer, contributing significantly towards the improvement in sensing performance. Therefore, the formation of hierarchical 2D heterostructure with electron depletion layer can be considered as a conducive way for the future development low-powered gas sensor.

Molybdenum-doped tungsten nitride coated with carbon shell and cobalt hydroxide nanosheets for efficient alkaline hydrogen evolution reaction

Water electrolysis is currently the most important way to achieve large-scale hydrogen (H2) production. Although many nonprecious electrocatalysts possess promising catalytic performance at low current density below 50 mA cm−2, it remains a substantial challenge to realize H2 production at industry-compatible current density over 500 mA cm−2. Here we have designed a hierarchical heterostructure of molybdenum-doped tungsten nitride coated with carbon shell and cobalt hydroxide nanosheets (Mo-WN@NC@Co(OH)2) for alkaline hydrogen evolution reaction (HER) with industrial current density and stability. The hybrid exhibits efficient alkaline HER activity, reaching the current density of 500 mA cm−2 at an overpotential of 196 mV. The Co(OH)2 nanosheets and Mo doping endow the composite with more active sites and enhanced intrinsic activity of the catalyst, as well as an appropriate water dissociation energy. In addition, the free energy of activation for each step during the HER process suggests a synergistic effect of Mo doping and Co(OH)2 in Mo-WN@NC@Co(OH)2 promoting surface Volmer and Heyrovsky steps during the HER process. This doping and interfacial engineering methods hold great promise for fabricating efficient nitride-based electrocatalysts for electrochemical energy devices.

Hierarchical heterostructure Ni2P hollow carbon spheres derived from MOFs for efficient electromagnetic wave absorption

In this study, a hierarchical heterogeneous structure of Ni2P hollow carbon spheres (Ni2P-HCS) was synthesized through a two-step process involving carbonization and phosphorization of Ni-metal organic framework (Ni-MOF) precursors. During the construction of the Ni2P/C nanostructure, heterointerface recombination and secondary graphitization were observed, which contribute to the modulation of interface polarization. Structural analysis revealed that the Ni2P/C nanoparticles are uniformly dispersed, forming stable porous structured microspheres, thereby leveraging dielectric and magnetic losses. The combination of Ni2P with metal-organic frameworks (MOFs) can optimize impedance matching, enhance effective absorption bandwidth, and consequently improve electromagnetic wave absorption performance. The results show that Ni2P-HCS (Ni2P-HCS700) exhibited superior electromagnetic wave (EMW) absorption characteristics when the carbonization temperature is 700 ℃. It achieves a maximum reflection loss (RL) of −46.7 dB at a thickness of 2.9 mm and an effective absorption bandwidth (EAB) of 4.8 GHz at 1.71 mm thickness, almost covering the Ku-band (13.3 GHz−18 GHz). Radar cross-section (RCS) simulations utilizing CST indicated an optimal RCS reduction value of 41 dB m² at theta=0° for Ni2P-HCS700. This work introduces a universal approach to designing high-performance lightweight absorbers derived from MOFs, incorporating transition metal phosphides to form composites for impedance matching control.

3D hierarchical flowerball-like CoSe2/MnSe nanosheet arrays as a novel electrode for electrochemical sensing of hydrazine

Hydrazine (N2H4) is considered to be a highly toxic substance harmful to human body and environment, and has received much attention in the field of electrochemical detection in recent years. In this study, 3D hierarchical flowerball-like CoSe2/MnSe nanosheet arrays (CoSe2/MnSe FNSAs) were obtained using CoMn-LDH as precursor and cobalt glycerate spheres as the sacrificial template by simple hydrothermal reaction and selenization method. Bimetal selenides have more active electrochemical activity and more abundant electrochemical redox reactions. The unique hierarchical flowerball-like nanosheet array heterostructure can accelerate ionic diffusion kinetics and improve electron transfer. As a hydrazine electrochemical sensor, CoSe2/MnSe FNSAs exhibits excellent electrocatalytic performance with a wide detection range of 0.001–7.45 mM and a low detection limit of 0.4 μM. This strategy provides a new choice for the detection of environmental organic pollutants.

Printable Block Molecular Assemblies with Controlled Exciton Dynamics.

Creating hierarchical molecular block heterostructures, with the control over size, shape, optical, and electronic properties of each nanostructured building block can help develop functional applications, such as information storage, nanowire spectrometry, and photonic computing. However, achieving precise control over the position of molecular assemblies, and the dynamics of excitons in each block, remains a challenge. In the present work, the first fabrication of molecular heterostructures with the control of exciton dynamics in each block, is demonstrated. Additionally, these heterostructures are printable and can be precisely positioned using Direct Ink Writing-based (DIW) 3D printing technique, resulting in programable patterns. Singlet excitons with emission lifetimes on nanosecond or microsecond timescales and triplet excitons with emission lifetimes on millisecond timescales appear simultaneously in different building blocks, with an efficient energy transfer process in the heterojunction. These organic materials also exhibit stimuli-responsive emission by changing the power or wavelength of the excitation laser. Potential applications of these organic heterostructures in integrated photonics, where the versatility of fluorescence, phosphorescence, efficient energy transfer, printability, and stimulus sensitivity co-exist in a single nanowire, are foreseen.

A hierarchical cerium metal organic framework-graphene oxide heterostructure composite for rapid and efficient scavenging of fluoride

The rational design of functional heretrostructures with integrated advantages for the efficient adsorption and removal of fluoride is important for water pollution control. In this study, a cerium metal organic framework-graphene oxide heterostructure composite (CeMOF@GO) is successfully prepared through ultrasonic irradiation and vapor diffusion-assisted interfacial growth. CeMOF@GO with hierarchical structure boosts the mass transport of fluoride with adsorption time reduced to 25 min. By virtue of the specific ligand exchange between adsorbed H2O/OH− at metal defect sites and fluoride ions, such unique CeMOF@GO can be utilized for fluoride removal, showing satisfactory adsorption capacity (151.5 mg g−1), excellent specific affinity (with a distribution coefficient of up to 21.865 L g−1), glorious salt tolerance (8.0 mol L−1 of nitrate), wide pH applicability and eminent recycling ability. The practical application of CeMOF@GO is well demonstrated by the selective scavenging of fluoride from diverse environmental water samples. This work is expected to provide a reliable defluorination approach, and bridge the gap between academic MOF-based adsorbent research and practical environmental application.

Fabrication of CoFe-LDH nanosheets@CoP nanowires hierarchical heterostructure with enhanced bifunctional electrocatalytic activity for alkaline water splitting

Exploring high active, low cost and stable electrocatalysts to replace noble precious metals has always been the major challenge in overall water splitting applications. Herein, CoFe-layered double hydroxide/Cobalt phosphide heterostructures on nickel foam (CoFe-LDH@CoP/NF) have been synthesized by using hydrothermal, chemical vapor deposition (CVD) and electrodeposition methods. The CoFe-LDH nanosheet is uniformly deposited on the surface of CoP nanowires to create the heterostructure. The formation of heterostructure increases active surface area, accelerates charge transfer velocity, optimizes the kinetics of reaction, thereby significantly improves electrocatalytic activity of the materials. The CoFe-LDH@CoP/NF attains 10 mA cm−2 with a low overpotential of 238 mV for OER and only 63 mV for HER. The catalyst provides the current density of 10 mA cm−2 throughout the overall water splitting by only requiring a low potential of 1.54 V. The CoFe-LDH@CoP/NF as an ideal electrocatalyst provides new ideas for developing efficient non-noble metal-based overall water splitting catalysts.

Preparation and photocatalytic properties of BNMT-BNNS/TiO2 hierarchical heterostructures

A novel one-dimensional boron nitride and titanium oxide hierarchical heterostructures (BNMT-BNNS/TiO2) composite photocatalyst endowed with high specific surface area was synthesized by molten salt assisted annealing and sol-gel method. With the increase of TiO2 concentration, the photocatalytic degradation efficiency of BNMT-BNNS/TiO2 hierarchical heterostructures increased first and then decreases, while the adsorption tended to decrease. When the molar ratio of TiO2 to BNMT-BNNS was 27:50, BNMT-BNNS/TiO2 displayed a higher specific surface area of 79.6770 m2g-1 than that of TiO2 (19.810 m2g-1). The methylene blue photodegradation rate of BNMT-BNNS/TiO2 is 99.62% after 115 min ultraviolet irradiation, show 1.62 times higher than that of the synthesized pure TiO2. The positive synergistic degradation mechanism between the strong adsorption of BNMT-BNNS support and the excellent photocatalysis of TiO2 was also discussed in detail. This work reports the synthesis of BNMT-BNNS/TiO2 photocatalysts with high surface area, excellent photocatalytic performance and reusability. BNMT-BNNS/TiO2 has potential applications in practical environmental purification.

Molybdenum-glycerate@zeolitic imidazolate framework spheres derived hierarchical nitrogen-doped carbon-encapsulated bimetallic selenides heterostructures for improved lithium-ion storage

Molybdenum-glycerate@zeolitic imidazolate framework spheres derived hierarchical nitrogen-doped carbon-encapsulated bimetallic selenides heterostructures for improved lithium-ion storage

Portable and highly enhanced surface enhanced Raman scattering and photocatalytic activity of cost-effective hierarchical hollow metal organic frameworks heterostructures induced by etched titanium sheet

In order to effectively detect and remove organic toxics in wastewater, the facile construction of plug and play bifunctional materials is very vital. Herein, a kind of metal-organic frameworks (MIL-53 (Fe) with hollow tubular structure was induced by an etched Ti sheet (ET), and then small sized Ag nanoparticles (Ag NPs) were in-situ anchored evenly on the internal and external surfaces of MIL-53 (Fe). Subsequently, a new type of bifunctional material (ETMA) was assembled. Surface enhanced Raman scattering (SERS) and photocatalytic activity of the material were investigated with crystal violet (CV, a carcinogenic and teratogenic toxic) as an analyte. The results found that trace amount of CV (1 × 10−12 M) can still be sensitively detected by the fabricated ETMA, and analysis enhancement factors as high as 6.9 × 105 even though only 1.39 wt % Ag was contained in the ETMA. Moreover, nearly 100 % of CV can be rapidly degraded by the ETMA after irradiated for 15 min, which was 44.47 times and 7.27 times faster than those of ET-Ag (ETA) and ET-MIL-53 (Fe) (ETM), respectively. Additionally, the removal efficiency of total organic carbon (TOC) was as high as 75.44 %. The remarkable enrichment effect, the strong interaction among components, and the synergistic effect in the target ETMA material were responsible to the dramatically enhanced SERS and photocatalytic performances. In addition, the cost-effective ETMA exhibited excellent uniformity, repeatability, stability, and recyclability towards the detection and removal of CV in actual water samples, showing great potentials in monitoring and removing organic pollutants in practical ecological environment.

Synthesized trimanganese tetraoxide functionalized zinc oxide hierarchical structures with abundant oxygen vacancies for ppb-level volatile organic compounds detection

Hierarchical heterostructures have been proven to be the great material structures for the fabrication of gas sensors, due to they high surface area, well-aligned porosity and synergy effect. Here, ZnO hierarchical structures with various amount of Mn dopant were synthesized through a simple one-step solution route followed by annealing treatment. The characterization results demonstrated that Mn dopant existed in the forms of Mn3O4 nanoparticles and lattice Mn2+ ions. The as-synthesized Mn3O4/ZnO hierarchical structures with abundant oxygen vacancies (MnxZnO with x values of 0, 0.25, 0.5, 1 and 3) were used as the sensing materials toward volatile organic compounds (VOCs) detection, illustrating that the introduction of Mn dopant can significantly improve the gas sensing performance. Especially, under optimal working temperature, Mn0.5ZnO hierarchical structures-based gas sensor exhibits the highest responses, fast response/recovery speed (2/9 s), a low detection limit (150 ppb), good selectivity and long-term stability toward acetone. In addition, the enhanced gas sensing mechanisms were explained by large surface area, oxygen vacancies and p-n heterojunction, boosting the surface reactions, which was further verified through DFT calculations. This work also confirmed that Mn element could be a promising dopant in metal oxides for high-performance VOCs gas sensors.

Hierarchical FeOxHy@Ni3B hybrid for efficient alkaline oxygen evolution at high current density

Electrocatalysts with high activity and long-term durability are vital toward large-scale hydrogen production from electrocatalytic water splitting. Here, the self-supported electrode (FeOxHy@Ni3B/NF) with hierarchical heterostructure was simply prepared by using Ni3B chunks grown on nickel foam as substrate to in situ form vertical FeOxHy nanosheets. Such hybrid shows efficient oxygen evolution reaction activity with overpotentials as low as 267 and 249 mV at 100 mA cm−2 in 1 M KOH solution and 30 wt% KOH solution, respectively. Meanwhile, it also exhibits excellent catalytic stability, sustaining catalysis at 500 mA cm−2 in 1 M KOH solution for 200 h, and even for 200 h at 1000 mA cm−2 in 30 wt% KOH solution. Further experimental results reveal that the FeOxHy@Ni3B/NF is endowed with superhydrophilic and superaerophobic surface properties, which not only provide more mass transport channels, as well as facilitated the diffusion of reaction intermediates and gas bubbles. Also, it holds faster reaction kinetics, more accessible active sites and accelerated electron transfer rates due to strong synergistic interactions at the heterogeneous interface.

Hollow α-Bi2O3/TiO2 nanotube arrays hierarchical heterojunction with strong interface interaction for efficient photocatalytic ciprofloxacin degradation

Interfacial regulation for photocatalyst is considered as an effective strategy to enhance visible-light utilization and charges transfer. But it is still a great challenge for the conscious design of interfacial engineering. Herein, hollow α-Bi2O3/TiO2 nanotube arrays (α-Bi2O3/TNAs) hierarchical heterojunction was constructed to modulate the interface structure for efficient photocatalytic degradation of ciprofloxacin (CIP). The systematic characterization analysis, density functional theory (DFT) calculations and electron paramagnetic resonance spectra revealed that the Z-scheme charges transfer mechanism was affirmed between α-Bi2O3 and TNAs. The hierarchical tubular heterostructure was contributed to enhancing light absorption, and the strong interfacial interaction could promote the separation and transfer of photogenerated charges. The optimal α-Bi2O3/TNAs exhibited higher photocatalytic activity for CIP (73.9 %) than TNAs (25.3 %) under visible-light irradiation. The anions and natural organic matters could decline CIP removal owing to competing active sites or aggravating radicals consumption. The theoretical calculations further demonstrated that the staggered energy levels produced an internal electric field at heterojunction interface to promote charges transfer. Three degradation pathways of CIP were proposed based on DFT calculations and LC-MS. The photocatalytic degradation of CIP by α-Bi2O3/TNAs could effectively reduce its toxicity, and eventually alleviate the environmental hazards of antibiotics.

Hierarchical structure promoted lithiation/delithiation behavior of a double-carbon microsphere supported nano-Co3O4 anode.

Due to limited mass loading, high-capacity electrode materials such as transition metal oxides (TMOs) are essential for microscale Li-ion batteries (LIBs) integrated in nano-/micro-electromechanical systems (N/MEMS). Unfortunately, their electrochemical performances are largely plagued by severe mechanical degradation and slow electron transport. Therefore, it is crucial to develop strategies that can improve the structural stability and electronic conductivity of TMO electrodes. In this work, double-carbon (carbon nanotubes and ketjen black) microsphere (DCMS) supported Co3O4 electrodes are fabricated simply through a spray drying and solvothermal method, which are designed to have a mesoporous three-dimensional (3D) hierarchical heterostructure containing well-dispersed Co3O4 nanoparticles within the DCMS framework. An in situ transmission electron microscopy (TEM) study reveals that the DCMS framework can not only provide facile strain accommodation, but also good electronic conductivity, leading to a much improved Li-storage performance compared to other Co3O4-based anodes. The hierarchical electrode exhibits maximum charge capacities of 1205.2 and 678.1 mA h g-1 at current densities of 0.1 and 2 A g-1, respectively, as well as a capacity retention of 92.2% at 0.3 A g-1 after 100 cycles. This study provides a low-cost, simple and general method for developing advanced high-capacity electrodes.

A Se-induced heterostructure electrode with polymetallic-CoNiFe towards high performance supercapacitors.

Rational regulation of electrode materials with high conductivity and unexceptionable cycling stability is crucial to meet the requirements of high-performance supercapacitors (SCs). Herein, a hierarchical porous kebab-like heterostructure (CoNiFe-Se) is prepared by a facile solvothermal reaction and selenization step. Both experimental and computational results demonstrate that incorporating Se via hydrothermal reaction contributes to modulating the morphology and electronic structure of transition metal carbonate hydroxides. The heterostructured electrode with abundant active sites composed of electroactive polymetallic-CoNiFe imparts excellent charge storage. Additionally, the unique structure of CoNiFe-Se with its heterogeneous interface, oxygen vacancies and cavities improves electrochemical activity, accelerates electron transfer and suppresses the volume expansion during the cycling. As a result, the CoNiFe-Se exhibits excellent electrochemical performance of 5040 mF cm-2 at 1 mA cm-2 and long-term durability with 85.7% retained capacitance after 10 000 cycles. Interestingly, an integrated asymmetric supercapacitor performs well for energy storage. This finding opens a new avenue for developing transition metal carbonate hydroxides using selenization strategies in the field of SCs.

A Brief Overview of the Morphological Characteristics of Cain2s4- based Photocatalysts and Their Influence on Boosting the Photocatalytic Behavior

CaIn2S4-based heterojunctions have gained significant attention as robust photocatalysts for sustainable environmental applications like organic degradation and H2 production. This study introduces a brief overview of the morphological characteristics of CaIn2S4-based composites and their effects on their catalytic properties. The fabrication of CaIn2S4- based photocatalysts with hierarchical or nanosheet heterostructures could offer an adequate surface area to volume ratio, enhancing the accessibility of pollutants to the catalyst surface and boosting the photodegradation performance. Moreover, the increased active sites reflect positive effects on the visible-light absorption efficiency. The perfect interfacial contact in the CaIn2S4-based composites facilitated the photocarrier transfer, hampered their reunion rate, prolonged their lifetime, and improved their utilization. The morphological durability and stability of CaIn2S4-based composites are also important variables influencing the photoreaction capacity. Finally, the optimization of surface states and morphological defects can modify the electronic structure of CaIn2S4-based semiconductors, improving their optical properties.