Light Utilization Rate Research Articles

Designing a hollow MoSe2/CuS nanospheres type-II heterojunction photocatalyst with superior UV-vis-NIR absorption for photocatalytic degradation of organic pollutants.

In this work, a hollow MoSe2/CuS type-II heterojunction was fabricated using hollow MoSe2 nanospheres as the basis for structural design. UV-Vis-NIR diffuse absorption tests show that MoSe2/CuS has a broad spectral absorption to extend the optical response range from UV-Vis to NIR. The light source utilization rate and interfacial area are increased by the hollow MoSe2/CuS core-shell structure. The broad absorption ability of MoSe2/CuS can facilitate the photocatalysis process. As the electrochemical impedance of MoSe2/CuS is lower than that of the MoSe2, MoSe2/CuS has a good photogenerated carrier separation efficiency. Benefiting from the synergistic facilitation effect of the multi-level 3D hollow nanosphere and the significant space charge region in type-II heterojunction, the RhB degradation efficiency of MoSe2/CuS reached 96.0% in 120.0minunder Xe (350W) broadband spectrum light irradiation. The photocatalysis mechanism of the hollow MoSe2/CuS core-shell structure was investigated. This work provides an insight into the application of broad spectrum semiconductor heterojunctions to solve environmental problems.

Mutual intercropping affects the growth and selenium content of cherry tomato seedlings

Intercropping can increase the utilization rate of light and water and can also improve plant growth. The objective of this study was to investigate the growth and selenium (Se) content in seedlings of three genotypes of cherry tomato under intercropping while applying Se. The pot experiment was conducted in a greenhouse. The monoculture of red, yellow and purple cherry tomato; among the three genotypes of cherry tomatoes, intercropping of two genotypes with each other, at the same time intercropping of three genotypes. These results show that the biomass increased under intercropping compared with monoculture. The chlorophyll b content of purple cherry tomato increased in different intercropping combinations. Furthermore, the net photosynthetic rate, stomatal conductance, and transpiration rate of purple were increased by intercropping with red and purple cherry tomatoes. The soluble protein and soluble sugar contents in yellow and purple cherry tomato increased by 49.13% and 8.37%, respectively, under mutual intercropping. Similarly, soluble sugar increased in purple cherry tomato by intercropping with yellow and red. The activities of superoxide and peroxidase in red and yellow cherry tomato seedlings were higher in all intercropping combinations than in monoculture, whereas free proline content and relative conductivity in all cherry tomatoes decreased. The Se content of roots, stem, and leaves in seedlings increased with intercropping. Therefore, intercropping can improve the growth and Se content of cherry tomatoes, and the combination of red, yellow and purple is better, which can be used to cultivate strong seedlings.

Unraveling the mystery of sandwich structure: Emerging photocatalytic hydrogen production by g-C3N5 coupled Nb2C MXene forming Schottky heterojunction

The development of new photocatalysts and photocatalytic systems is the essence of the development of photocatalytic hydrogen production engineering. Nitrogen-rich graphite carbon nitride (g-C3N5) has gradually replaced conventional graphite phase carbon nitride (g-C3N4) with a smaller bandgap and high-efficiency visible light utilization. In this study, g-C3N5 and Nb2C MXene coupled composition with sandwich structure were manufactured by a simple ultrasonic magnetic stirring method and used for photocatalytic hydrogen production. By adjusting the ratios of single components in the system, the hydrogen production rate of the optimal sample 4:1g-C3N5/Nb2C under visible light irradiation is 2529.5 μmol·g−1·h−1, which is 21 times higher than that of g-C3N5. The high apparent quantum yield (AQY) value of 17.3 % also proves a high light utilization rate. The atomic force microscopy (AFM) technique reveals variations in the thickness of the samples, while strongly demonstrating the formation of sandwich structure. In addition, X-ray photoelectron spectroscopy (XPS) analysis further reveals the electron transfer paths within the system, preliminarily verifying the formation of Schottky heterojunctions. Kelvin probe force microscopy (KPFM) tests not only re-validate the correctness of the electron transfer path but also demonstrate the accuracy of the energy bands. The density-functional theory (DFT) calculations corroborate that Nb2C MXene plays the role of a photoco-catalyst to form Schottky heterojunctions with g-C3N5 for efficient carrier separation and migration. This work highlights the key role of sandwich structure photocatalytic systems on photocatalytic performance.

Energy band engineering of graphitic carbon nitride for photocatalytic hydrogen peroxide production

AbstractHydrogen peroxide (H2O2) is one of the 100 most important chemicals in the world with high energy density and environmental friendliness. Compared with anthraquinone oxidation, direct synthesis of H2O2 with hydrogen (H2) and oxygen (O2), and electrochemical methods, photocatalysis has the characteristics of low energy consumption, easy operation and less pollution, and broad application prospects in H2O2 generation. Various photocatalysts, such as titanium dioxide (TiO2), graphitic carbon nitride (g‐C3N4), metal‐organic materials, and nonmetallic materials, have been studied for H2O2 production. Among them, g‐C3N4 materials, which are simple to synthesize and functionalize, have attracted wide attention. The electronic band structure of g‐C3N4 shows a bandgap of 2.77 eV, a valence band maximum of 1.44 V, and a conduction band minimum of −1.33 V, which theoretically meets the requirements for hydrogen peroxide production. In comparison to semiconductor materials like TiO2 (3.2 eV), this material has a smaller bandgap, which results in a more efficient response to visible light. However, the photocatalytic activity of g‐C3N4 and the yield of H2O2 were severely inhibited by the electron‐hole pair with high recombination rate, low utilization rate of visible light, and poor selectivity of products. Although previous reviews also presented various strategies to improve photocatalytic H2O2 production, they did not systematically elaborate the inherent relationship between the control strategies and their energy band structure. From this point of view, this article focuses on energy band engineering and reviews the latest research progress of g‐C3N4 photocatalytic H2O2 production. On this basis, a strategy to improve the H2O2 production by g‐C3N4 photocatalysis is proposed through morphology control, crystallinity and defect, and doping, combined with other materials and other strategies. Finally, the challenges and prospects of industrialization of g‐C3N4 photocatalytic H2O2 production are discussed and envisioned.

Enhanced visible light photocatalytic activity of SDBS/C/Nd/TiO2 synthesized by using anionic surfactant SDBS as template agent

<p>The catalyst SDBS/C/Nd/TiO2 was synthesized by sol-gel method using TiO2 co-doped with C and Nd and anionic surfactant SDBS as template agent. The prepared photocatalysts were characterized by X-ray diffraction (XRD), scanning electron (SEM), X-ray photoelectron spectrometer (XPS) and UV-vis diffuse reflectance spectroscopy (UV-vis DRS) and so on. Experimental results show that the crystal structure of the catalytic material is anatase type. Since doped elements change the energy band structure and electronic structure of TiO2, photogenerated electrons and holes can transition through the intermediate energy level, resulting in a decrease in the required excitation energy, thereby increasing the distance of its absorption edge moving toward the long wave direction, and meanwhile improving the utilization rate of visible light. The bandgap energy of the catalyst SDBS/C/Nd/TiO2 was 2.78 eV. Compared to pure TiO2 (3.1 eV), the band gap is reduced by 0.32eV. The photocatalytic experiments show that the degradation rate of the catalyst SDBS/C/Nd/TiO2 for methyl orange solution can reach 67%, and the catalytic performance is much improved than that of pure TiO2.</p>

Light-Field Optimization of Deep-Ultraviolet LED Modules for Efficient Microbial Inactivation

Public awareness of preventing pathogenic microorganisms has significantly increased. Among numerous microbial prevention methods, the deep-ultraviolet (DUV) disinfection technology has received wide attention by using the nitride-based light-emitting diode (LED). However, the light extraction efficiency of DUV LEDs and the utilization rate of emitted DUV light are relatively low at the current stage. In this study, a light distribution design (referred to as the reflective system) was explored to enhance the utilization of emitted DUV from LEDs, leading to successful and efficient surface and air disinfection. Optical power measurements and microbial inactivation tests demonstrated an approximately 79% improvement in average radiation power density achieved by the reflective system when measured at a 5 cm distance from the irradiation surface. Moreover, a statistically significant enhancement in local surface disinfection was observed with low electric power consumption. The reflective system was integrated into an air purifier and underwent air disinfection testing, effectively disinfecting a 3 m3 space within ten minutes. Additionally, a fluorine resin film at the nanolevel was developed to protect the light module from oxidation, validated through a 1200 h accelerated aging test under humid conditions. This research offers valuable guidance for efficient and energy-saving DUV disinfection applications.

Flexible nanoimprint lithography enables high-throughput manufacturing of bioinspired microstructures on warped substrates for efficient III-nitride optoelectronic devices

III-nitride materials are of great importance in the development of modern optoelectronics, but they have been limited over years by low light utilization rate and high dislocation densities in heteroepitaxial films grown on foreign substrate with limited refractive index contrast and large lattice mismatches. Here, we demonstrate a paradigm of high-throughput manufacturing bioinspired microstructures on warped substrates by flexible nanoimprint lithography for promoting the light extraction capability. We design a flexible nanoimprinting mold of copolymer and a two-step etching process that enable high-efficiency fabrication of nanoimprinted compound-eye-like Al2O3 microstructure (NCAM) and nanoimprinted compound-eye-like SiO2 microstructure (NCSM) template, achieving a 6.4-fold increase in throughput and 25% savings in economic costs over stepper projection lithography. Compared to NCAM template, we find that the NCSM template can not only improve the light extraction capability, but also modulate the morphology of AlN nucleation layer and reduce the formation of misoriented GaN grains on the inclined sidewall of microstructures, which suppresses the dislocations generated during coalescence, resulting in 40% reduction in dislocation density. This study provides a low-cost, high-quality, and high-throughput solution for manufacturing microstructures on warped surfaces of III-nitride optoelectronic devices.

Effect of Rare-Earth Compounds on the Photocatalytic Performance of ZnIn2S4: A Review

Semiconductor photocatalysis is considered one of the efficient and clean environmental technologies in the treatment of organic dye wastewater. Indium zinc sulfide (ZnIn2S4) is favored among many photocatalysts because of its narrow-forbidden bandwidth, good visible light absorption properties, suitable conduction and valence band positions, high chemical stability, low cost, easy preparation and low toxicity. However, indium zinc sulfide (ZnIn2S4) still faces the disadvantages of low visible light utilization and high photogenerated carrier complexation rate. In this paper, we introduce rare-earth ion doping and heterojunction of rare-earth oxides with ZnIn2S4 to improve photocatalytic efficiency, and we also review the current research status and development prospects of indium zinc sulfide in recent years.

Bathocuproine, an old dog, new tricks for boosting the performance of perovskite solar cells

Perovskite solar cells (PSCs) have demonstrated extensive prospects for future applications. However, defects remain the crucial factor that impedes their further advancement in performance, and passivation of the interfaces (such as the buried and/or top interfaces) is regarded as one of the most effective approaches. Herein, we aim to address another important interface, namely, the indium tin oxide/electron transport layer (ITO/ETL) interface in n-i-p structured devices. Since electron transport layers are typically fabricated using commercial nanotin dioxide, which often displays insufficient density. To combat this, we employ the most commonly used bathocuproine (BCP) material to treat the ITO/ETL interface. The incorporation of BCP diminishes the direct contact between the perovskite and ITO layers while also passivating the buried interface and adjusting the crystal orientation of perovskites. Furthermore, the substrate layer exhibits improved transparency, consequently elevating the utilization rate of light by perovskite. As a result, the BCP-based PSC exhibits an impressive efficiency greater than 22%, surpassing the control one of 19.91%, and simultaneously demonstrates excellent stability. Notably, the optimization of this interface has universal applicability for the improvement of PSCs performance.

Copper-decorated strategy based on defect-rich NH2-MIL-125(Ti) boosts efficient photocatalytic degradation of methyl mercaptan under sunlight

Photocatalysis has received significant attention as a technology that can solve environmental problems. Metal-organic frameworks are currently being used as novel photocatalysts but are still limited by the rapid recombination of photogenerated carriers, low photogenerated electron migration efficiency and poor solar light utilization rate. In this work, a novel photocatalyst was successfully constructed by introducing Cu species into thermal activated mixed-ligand NH2-MIL-125 (Ti) via defect engineering strategy. The constructed defect structure not only provided 3D-interconnected gas transfer channels, but also offered suitable space to accommodate introduced Cu species. For the most effective photocatalyst 0.2Cu/80%NH2-MIL-125 (300 °C) with optimized Cu content, the photocatalytic degradation rate of CH3SH achieved 4.65 times higher than that of pristine NH2-MIL-125 under visible light (λ > 420 nm). At the same time, it showed great degradation efficiency under natural sunlight, 100 ppm CH3SH was completely removed within 25 min in full solar light illumination. The improved catalytic efficiency is mainly due to the synergistic effect of the integrated Schottky junction and rich-defective NH2-MIL-125, which improved the bandgap and band position, and thus facilitated the separation and transfer of the photo-generated carriers. This work provided a facile way to integrate Schottky junctions and rich-defective MOFs with high stability. Due to its excellent degradation performance under sunlight, it also offered a prospective strategy for rational design of high-efficiency catalysts applied in environmental technologies.

Ice templated and ice seed tailored hydrogels for highly efficient solar evaporator

In recent years, freshwater resources have become a global concern, and solar vapor generation (SVG) has garnered significant attention from researchers. Herein, a novel hydrogel solar evaporator was prepared by incorporating lignin and CuS-rGO into a chitosan-gelatin matrix. The anisotropic and isotropic morphologies of the hydrogel were prepared by pathway control on the solidification velocities of ice crystals and ice seeds. It presented that the anisotropic morphology can improve the refraction of light and increase the utilization rate of light by forming a light trap, leading to higher water evaporation rate. Additionally, ice seed was introduced during the freezing process, producing an anisotropic hydrogel with curled layer structure that endowed lower enthalpy of water evaporation and faster water transfer rate, resulting in high evaporate of 3.62 kg m−2 h−1 under one solar irradiation with photothermal conversion efficiency of 97.7 %. Finally, the gel also demonstrated good mechanical properties, long-term working stability and harsh environment tolerance, which make it ideal for outdoor applications. The hydrogel evaporator had potential to generate 25.24 kg m2 water per day that could meet the huge demand for freshwater as sources.

Construction of an interpenetrating manganese residue-derived FeC2O4/CuC2O4 composite with enhanced charge transfer in photo-Fenton reactions via mechanical activation pre-anchoring strategy

The low rates of charge separation and migration and the pronounced photo-corrosion of FeC2O4 significantly limit its environmental applications. Strengthening the charge transfer rate by constructing a tight bimetallic interface is an attractive method. Herein, a novel interpenetrating manganese residue (MR)-derived FeC2O4/CuC2O4 (MAMR-FeCuOx) composite with intimate interface was constructed via mechanical activation (MA) pre-anchoring and liquid-phase deposition-photo-reduction strategy, and was used as a photo-Fenton catalyst for efficient degradation of oxytetracycline (OTC) under visible light irradiation. The Cu2+ was uniformly dispersed and anchored on the surface of MR after MA pretreatment and an interpenetrating structure was formed through the liquid-phase deposition-photo-reduction process. MAMR-FeCuOx displayed excellent photo-Fenton catalytic performance and stability with a 99% OTC removal rate within 10 min, which is 20.87 times higher than that of FeC2O4, and maintained over 96% OTC removal rate even after ten consecutive cycles. These enhanced catalytic performances and stability can be attributed to the formation of an interpenetrating structure with the intimate interface between FeC2O4 and CuC2O4 induced by MA pretreatment, which promoted electronic interactions between Fe and Cu for effectively reducing the charge transfer barriers. This improved the utilization rate of visible light, the interface electron migration, and the separation efficiency of photogenerated charge carriers. This study provides new insights into the valorization of solid waste and the development of stable and efficient FeC2O4-based catalysts.

Dodecahedral hollow multi-shelled Co3O4/Ag:ZnIn2S4 photocatalyst for enhancing solar energy utilization efficiency.

Employing semiconductor photocatalysts featuring a hollow multi-shelled (HoMs) structure to establish a heterojunction is an effective approach to addressing the issues of low light energy utilization and severe recombination of photogenerated charge carriers. To take advantage of these key factors in semiconductor photocatalysis, here, a dodecahedral HoMs Co3O4/Ag:ZnIn2S4 photocatalyst (denoted as Co3O4/AZIS) was firstly synthesized by coupling Ag+-doped ZnIn2S4 (AZIS) nanosheets with dodecahedral HoMs Co3O4. The unique HoMs structure of the photocatalyst can not only effectively promote the separation and transfer of photo-induced charge, but also improve the utilization rate of visible light, exposing rich active sites for the photocatalytic redox reaction. The photocatalytic experiment results showed that the Co3O4/90.0 wt% AZIS photocatalyst has a high hydrogen (H2) production rate (695.0 μmol h-1 g-1) and high methyl orange (MO) degradation rate (0.4243 min-1). This work provides a feasible strategy for the development of HoMs heterojunction photocatalysts with enhanced H2 production and degradation properties of organic dyes.

Enhancing activity and non-deactivating stability on N-modified TiO2 catalyst for visible-light photocatalytic oxidation of ammonia at room temperature

Nitrogen modified TiO2 catalysts (N-TiO2(1)) with high photocatalytic activity and non-deactivating stability were prepared by using urea as nitrogen source. Its efficiency of photocatalytic oxidation of NH3 (NH3-PCO) remained above 80 %, peaking at 88 % at room temperature over 72 h, while N2 selectivity also improved noticeably, stabilizing at approximately 87.1 %. Conversely, the NH3 conversion on pure TiO2 plateaued at approximately 67 % within 72 h, peaking at only 72.8 %, with nitrogen selectivity not exceeding 55 %. N element was successfully doped into TiO2 lattice system in the form of O-Ti-N, which reduced the band gap energy from 3.18 eV to 3.07 eV and improved the light utilization rate. The water molecules formed during the reaction contribute to the in-situ reaction to continually generate hydroxyl radicals (·OH), thereby conferring greater reaction stability. By-products NOx- and NOx are formed during the reaction process, while NOx will be also converted to N2 by initial selective catalytic reduction (i-SCR) mechanism. These findings present a novel perspective for enhancing the stability of NH3-PCO active agents and have substantial applications within the parameters of air pollution control.

Self-assembled B-doped flower-like graphitic carbon nitride with high specific surface area for enhanced photocatalytic performance

Graphitic carbon nitride (g-C3N4) is a promising nonmetallic photocatalyst. In this manuscript, B-doped 3D flower-like g-C3N4 mesoporous nanospheres (BMNS) were successfully prepared by self-assembly method. The doping of B element promotes the internal growth of hollow flower-like g-C3N4 without changing the surface roughness structure, resulting in a porous floc structure, which enhances the light absorption and light reflection ability, thereby improving the light utilization rate. In addition, B element provides lower band gap, which stimulates the carrier movement and increases the activity of photogenerated carriers. The photocatalytic mechanism and process of BMNS were investigated in depth by structural characterization and performance testing. BMNS-10 % shows good degradation for four different pollutants, among which the degradation effect on Rhodamine B (RhB) reaches 97 % in 30 min. The apparent rate constant of RhB degradation by BMNS-10 % is 0.125 min−1, which is 46 times faster compared to bulk g-C3N4 (BCN). And the photocatalyst also exhibits excellent H2O2 production rate under visible light. Under λ > 420 nm, the H2O2 yield of BMNS-10 % (779.9 μM) in 1 h is 15.9 times higher than that of BCN (48.98 μM). Finally, the photocatalytic mechanism is proposed from the results of free radical trapping experiments.

Synergetic enhancement effect of two-dimensional MoS2 nanosheets and metal organic framework-derived porous ZnO nanorods for photodegradation performance.

Two-dimensional transition metal dichalcogenides and semiconductor metal oxides have shown great potential in photocatalysis. However, their stability and efficiency need to be further improved. In this paper, porous ZnO nanorods with high specific surface area were prepared from metal-organic framework ZIF-8 by a simple hydrothermal method. A MoS2/ZnO composite was constructed by loading MoS2 onto the surface of porous ZnO nanorods. Compared with ZnO materials prepared by other methods, MoS2/ZnO prepared in this paper exhibits superior photocatalytic performance. The enhanced photocatalytic activity of the MoS2/ZnO composite can be attributed to the formation of heterojunctions and strong interaction between them, which greatly facilitate the separation of electrons and holes at the contact interface. In addition, due to the wide absorption region of the visible spectrum, MoS2 can greatly broaden the light absorption range of the material after the formation of the composite material, increase the utilization rate of visible light, and reduce the combination of electrons and holes. This study provides a new way to prepare cheap and efficient photocatalysts.

Comparison of Modification Methods of Photocatalyst G-C3N4 in Hydrogen Production Performance

Non-metallic polymer semiconductor graphite phase carbon nitride (g-C3N4) is a low-cost, environmentally friendly raw material with suitable bandgap width and stable chemical properties. However, there are still problems such as lower surface area, higher recombination rate of photo-excited charge carriers, and lower utilization rate of visible light. This paper introduces the structure, physicochemical properties, preparation methods, and modification ideas of graphite phase carbon nitride, focusing on several popular modification achievements in recent years, as well as a horizontal comparison of their respective production methods, mechanisms, and hydrogen production efficiency. Finally, the challenges and prospects in the modification of carbon nitride are discussed.

Fabrication of WO3 photocatalyst by plasma assisted ball milling under different discharge atmospheres

A convenient method for producing single oxide WO3-x at room temperature through plasma milling was reported, resulting in a highly efficient visible-light photocatalyst. By altering the discharge atmosphere during plasma milling from ammonia and nitrogen to argon, the color of the milled monoclinic WO3 powders deepens from blue to dark blue, indicating an increased concentration of oxygen vacancies. The morphological and structural properties of the monoclinic WO3 powders, prepared using different ball milling techniques, are characterized using XRD, SEM, TEM, Raman, XPS, EPR, and UV–vis. These results reveal that plasma milling leads to a higher surface area, increased presence of oxygen vacancies, and more defects compared with conventional milling, resulting in a greater number of more reactive sites and a larger contact area between monoclinic WO3 nanoparticles and RhB solution. Consequently, monoclinic WO3 samples fabricated through Ar-P-milling exhibit the highest photocatalytic activity. This is attributed to the reduction of the WO3−x band gap to 2.28 eV by Ar-P-milling with high oxygen vacancies. This lower bandgap markedly improves the light utilization rate, thereby enhancing the overall photocatalytic efficiency. The Ar-P-milled WO3 shows the highest degradation rate constant of 0.037 min−1, which is 4 times higher than that of pure monoclinic WO3.

Ce3+-Yb3+, Tb3+-Yb3+ and Pr3+-Nd3+-Yb3+ mixed-doped TeO2–ZnO–Na2O glasses for enhancing the efficiency of silicon solar cells

In general, the sunlight wavelength absorbed by silicon solar cells is mainly concentrated in the range of 600–1100 nm. Although silicon solar cells can also absorb sunlight in the ultraviolet and visible regions with <600 nm, the utilization of light is very low. In addition, some high-energy photons in the ultraviolet and visible region can cause serious damage to silicon solar panels, reducing its useful lifetime and lowering its photoelectric conversion efficiency. Therefore, in order to make full use of the light in this range, we studied three-layer light-conversion glass doped with three groups of rare-earth ion to improve the utilization rate of light in silicon solar cells and prolong the lifetime. A series of zinc tellurate glasses (TeO2–ZnO–Na2O) doped with Ce3+-Yb3+, Tb3+-Yb3+ and Pr3+-Nd3+-Yb3+, respectively, were prepared by melting quenching method. The crystalline state and interior structure of the prepared glasses are characterized by using X-ray diffraction (XRD) spectra and Raman spectra. And the lowest phonon energy of these glasses is about 773 cm−2. The photoluminescence properties of rare-earth ions doped in these glasses are studied. The results show that the near infrared emission (centered at 980 nm) of activator ion (Yb3+) is observed when the sensitizer ions (Ce3+, Tb3+, Pr3+ and Nd3+) are excited by using 430 nm, 355 nm and 488 nm ultraviolet and visible (UV–vis) photons, respectively. The down-conversion and down-shift energy transfer mechanisms between sensitizer ion and activator ion are discussed. Based on the above research, a triple-layer zinc tellurate glass sample doped with Ce3+-Yb3+/Tb3+-Yb3+/Pr3+-Nd3+-Yb3+ in a certain ratio is prepared. And the current density-voltage (J-V) curves of silicon solar cell covered with triple-layer zinc tellurate glass were tested. According to the data obtained from J-V curves, the relative efficiency (Δη) of Si solar cells covered with Ce3+-Yb3+/Tb3+-Yb3+/Pr3+-Nd3+-Yb3+ triple-layer zinc tellurate glass is increased by 2.37% compared with that of silicon solar cell covered with blank glass. So, the above results can show that the glass has important application values in improving the energy efficiency of silicon solar cells.

A novel sea urchin-shaped copper-incorporated g-C3N4 nanoreactor for high-efficiency selectivity photocatalytic CO2 conversion into CO

Carbon graphene nitride (g-C3N4, CN) is a promising future for photocatalytic CO2 conversion into solar fuels. However, its photocatalytic activity and selectivity are limited to inadequate active sites, low visible light utilization rate, poor CO2 adsorption capacity, and rapid photo-generated carriers recombination rate. Herein, the supramolecular self-assembly method synthesized the sea urchin-like Cu-incorporated g-C3N4 (Cu-CNNTs) nanoreactors. The as-prepared Cu-CNNTs nanoreactor exhibits the photocatalytic reduction of CO2 into CO rate (16.09 μmol g-1h−1), 9.4 times higher than BCN and 3.33 times that of CNHS. The Cu-doping in the six-fold cavity of heptazine units as reaction active centers enrich both the photoelectrons and CO2 molecule. The superior structure of Cu-CNNTs shortens the transmission distance of electrons, accelerating the separation of electron-hole pairs and improving the utilization of light. Theory calculation results demonstrate that the activation energy barrier of the reduction of CO2 to CO is lower than that of CH4. Therefore, Cu-CNNTs exhibit enhanced selectivity and photocatalytic activity for converting CO2 to CO. This result provides valuable insights for the design and synthesis of highly selective and active carbon nitride-based multifunctional photocatalysts.