Formation Of Heterojunction Research Articles

Photo-crosslinking and layer-by-layer processed organic photodetectors with remarkably suppressed dark current

The effective reduction of dark (or noise) current presents a significant hurdle in enhancing the detectivity of organic photodetectors (OPDs). To address this challenge, a photo-crosslinkable donor polymer, PM6-Br50, is synthesized by introducing bromoalkyl side-chains onto the PM6 structure. This modification enables the formation of a pseudo planar heterojunction (p-PHJ) structure of crosslinked donor/acceptor through a layer-by-layer (LbL) sequential process without the necessity for an semi-orthogonal solvent. This innovation effectively overcomes solvent-related limitations in the LbL process. Additionally, we replace the semi-metallic hole-transport layer (HTL), PEDOT:PSS, with a semiconducting conjugated polyelectrolyte (TPAFS-TMA) with a high conduction band. The p-PHJ configuration, featuring pure donor/anode and pure acceptor/cathode contacts, enhances the charge injection barrier for electrons (holes) from the anode (cathode) in the dark under reverse bias, effectively minimizing dark current. Furthermore, the TPAFS-TMA HTL serves to impede electron injection from the anode. Through the synergistic combination of these two strategies, a significantly reduced dark current density (4.03 × 10−10 A cm−2) is measured by four orders of magnitude, compared to the bulk heterojunction OPDs with PEDOT:PSS. Furthermore, we measure remarkably high shot noise-based and total noise current-based specific detectivities of 4.27 × 1013 and 6.97 × 1012 cm Hz1/2 W−1 (with linear dynamic range of 73.7 dB), respectively.

Natural sunlight energy harvesting using NiAl2O4@N-rGO hetero-junction for photocatalytic degradation of crystal violet dye: Kinetic and mechanistic insights

In this study, NiAl2O4 (NA) was synthesized by the co-precipitation route and its hetero-junctions were fabricated with N-doped reduced graphene oxide (N-rGO) through the ultra-sonication method. The structural, morphological, magnetic, optical and photocatalytic properties of synthesized NA, N-rGO, and the NA@N-rGO 1–4 hetero-junctions characterized by XRD, FTIR, SEM, VSM, PL and UV–visible spectroscopy, respectively. XRD results showed that crystallite size decreases from 25.01 nm (NA) to 15.20 nm for NA@N-rGO-4 and porosity increases up to 77.7 % for NA@N-rGO-4 making it remarkable for photocatalytic applications and FTIR results confirmed the formation of N-rGO as well as its successful integration into NA matrix, resulting in the formation of hetero-junctions. Magnetic properties were investigated using a vibrating sample magnetometer (VSM), revealing distinctive S-shaped hysteresis loops at 25 °C for both NA and N-rGO, as well as the NA@N-rGO 1–4 hetero-junctions and magnetic saturation decreases with an increase in N-rGO content as for NA@N-rGO-4 Ms drops to 0.0038 emu/g. Notably, the bandgap of NA@N-rGO-4 hetero-junction was effectively reduced from 3.0 eV (in the case of NA) to 2.1 eV, resulting in a discernible decrease in photoluminescence (PL) intensity and increase in e--h+ pair separation. Under visible light, NA@N-rGO-4 exhibited a remarkable 94.68 % efficiency in crystal violet (CV) dye degradation within just 90 min, outperforming NA's 59.05 % degradation efficiency and OH. Radicals play a major contribution to the degradation of dye. The optimization of degradation capabilities was achieved through the manipulation of catalyst dosage, dye concentration and varying pH values for the degradation of CV dye. NA@N-rGO-4 hetero-junction demonstrates the considerable potential for efficient dye degradation in wastewater under visible light, owing to its exceptional catalytic performance.

The construction of Z-scheme heterojunction ZnIn2S4@CuO with enhanced charge transfer capability and its mechanism study for the visible light degradation of tetracycline

In this study, copper oxide (CuO) was prepared by the microwave-assisted hydrothermal technique subsequently, CuO was grown in situ onto different rare metal compounds to prepare Z-scheme heterojunctions to improve the degradation efficiency of tetracycline (TC) in water environments. Various characterization proved the successful synthesis of all composite materials, and the formation of tight heterojunction interfaces, among which, the core–shell structure ZnIn2S4@CuO exhibited excellent photocatalytic degradation capability. Research results indicated that the degradation efficiency of ZnIn2S4@CuO for TC (50 mg/L) in the water environment reached 95.8 %, and the degradation rate is 2.41 times and 12.93 times that of CuO and ZnIn2S4 alone, respectively, the reason is because of the introduction of ZnIn2S4, Z-scheme heterojunction structures and internal electric field (IEF) is constructed and formed to extend the visible light response range of photocatalysts to improve electron-hole separation efficiency, and enhance charge transfer. In addition, ZnIn2S4@CuO-2 exhibited good stability and reproducibility, with no significant loss of activity after five cycles. Finally, the precise locations of free radical attack on TC were investigated by the combined use of high-resolution mass spectrometry (HR-MC) and frontier electron densities (FEDs), and a reasonable degradation pathway was provided. The results of this research provide a new and viable approach to overcome the limitations of conventional photocatalytic materials in terms of limited visible light absorption range and fast carrier recombination rates, which offers promising prospects for a wide range of applications in the field of wastewater purification.

Chemiresistive n-butanol gas sensors based on Co3O4@ZnO hollow-sphere-array thin films prepared by template-assisted magnetron sputtering

Rapid and accurate detection of n-butanol in the environment is crucial owing to its negative effects on human health. Herein, gas sensors based on Co3O4@ZnO hollow-sphere-array thin films modified using Au particles are successfully prepared via template-assisted magnetron sputtering for detecting n-butanol. The best sensor performances are achieved when the thicknesses of the sputtered ZnO and Co3O4 films are 60 and 1.2 nm, respectively, and the sputtering time of the Au particles is 10 s. Furthermore, the best sensor exhibits an exceptionally high response to an n-butanol concentration of 100 pm at 275 °C (Ra/Rg = 260), a short response/recovery time (1 s/92 s), a considerably lower limit of detection (Ra/Rg = 5.8 at n-butanol concentration = 100 ppb) as well as high selectivity and repeatability. The remarkable sensing performance of the proposed sensors can be mainly attributed to the charge transfer induced by the Co3O4–ZnO heterojunction formation and the catalytic and spillover effects of the Au particles. This study is important because it provides a simple preparation method for high-performance semiconductor gas sensors using magnetron sputtering, which would enable future large-scale and integrated preparation of high-performance gas sensors.

Molybdenum sulfide/Ni:FeOOH heterostructures as efficient water oxidation electrocatalysts in alkaline media

Sluggish oxygen evolution reaction (OER) is considered to be the bottleneck that restricts the usage of electrocatalytic water splitting to generate hydrogen. With this in mind, we demonstrate the design and preparation of a series of Mo15S19/Ni:FeOOH heterostructures toward water oxidation. As expected, the considerable acceleration of OER process is achieved by the combination of Mo15S19 with Ni:FeOOH, due to the formation of heterojunction. Under the optimized conditions, the as-prepared Mo15S19/Ni:FeOOH-21 exhibits a lower overpotential (214 mV vs RHE at 10 mA cm−2) than other control samples. The OER activity of Mo15S19/Ni:FeOOH-21 is found to be comparable to and/or better than the state-of-the-art OER electrocatalysts reported in the literature recently, making it a promising OER electrocatalyst in the industrial water electrolysis. This work opens up an efficient avenue to rational design of other high-performance composite OER electrocatalysts.

Lithium manganite anchored on mesoporous ceria photocatalyst for removal of Hg(II) ions from aqueous solution under visible illumination

The development of effective photocatalysts is critical for the photo/redox reaction of noxious Hg(II) ions and Hgo in environmental engineering and purification. In this contribution, Li2MnO3 nanoparticles (NPs) were anchored mesoporous CeO2 networks to design photocatalysts with high harvest of visible light, and the obtained Li2MnO3/CeO2 nanocomposites were utilized for photoreduction of Hg(II) ions under visible illumination. The TEM and XRD results showed the formation of Li2MnO3 and CeO2 with the monoclinic and cubic fluorite structures, and the particle size is about 10–20 nm. The enhancement of light absorption of Li2MnO3/CeO2 nanocomposites could create considerable photoinduced carriers during the photocatalytic reactions. The incorporation of Li2MnO3 and CeO2 NPs demonstrated outstanding photocatalytic performance compared with pristine CeO2 NPs, and the optimum 9%Li2MnO3/CeO2 nanocomposite achieved 98 % of the reduction Hg(II) ability within 60 min. The rate constant for 9 % Li2MnO3/CeO2 photocatalyst is ∼ 6.47 and 3.85 times greater than Li2MnO3 and CeO2 NPs. The superior photocatalytic performance of Li2MnO3/CeO2 nanocomposites was ascribed to the efficient separation of photocarriers due to the formation of S-scheme heterojunction, the large surface area, and mesoporous structures. The obtained Li2MnO3/CeO2 nanocomposite was highly stable and efficient for the Hg(II) photoreduction runs up to five successive experiments under similar conditions. Moreover, the possible mechanism over heterojunctions Li2MnO3/CeO2 nanocomposites toward the reduction of Hg(II) ions is examined as well. The formation of S-scheme heterojunction photocatalyst provides better photocatalytic applications in terms of air purification, hydrogen production, and water treatment.

NiGa2O4 interfacial layers in NiO/Ga2O3 heterojunction diodes at high temperature

NiO/Ga2O3 heterojunction diodes have attracted attention for high-power applications, but their high temperature performance and reliability remain underexplored. Here, we report the time evolution of the electrical properties in the widely studied p-NiO/n-Ga2O3 heterojunction diodes and formation of NiGa2O4 interfacial layers at high temperatures. Results of our thermal cycling experiment show an initial leakage current increase which stabilizes after sustained thermal load, due to reactions at the NiO–Ga2O3 interface. High-resolution TEM microstructure analysis of the devices after thermal cycling indicates that the NiO–Ga2O3 interface forms a ternary compound at high temperatures, and thermodynamic calculations suggest the formation of the spinel NiGa2O4 layer between NiO and Ga2O3. First-principles defect calculations find that NiGa2O4 shows low p-type intrinsic doping and hence can serve to limit electric field crowding at the interface. Vertical NiO/Ga2O3 diodes with intentionally grown ∼5 nm thin spinel-type NiGa2O4 interfacial layers show an excellent device ON/OFF ratio of >1010 (± 3 V), VON of ∼1.9 V, and increased breakdown voltage of ∼1.2 kV for an initial unoptimized 300 μm diameter device. These p–n heterojunction diodes are promising for high-voltage, high temperature applications.

MOF-derived CoFe2O4/FeS2 Z-type heterojunctions for efficient degradation of tetracycline by visible-light activation of persulfate

CoFe2O4 was successfully prepared by calcination of bimetallic MOF precursors, and CoFe2O4/FeS2 nanocomposites were prepared by compounding it with FeS2. The catalysts were characterized for their photocatalytic ability using tetracycline (TC) as a target contaminant. The high adsorption due to the wide specific surface area of MOF-derived CoFe2O4/FeS2 led to its excellent photocatalytic performance. Furthermore, the optimum dosages of catalyst and persulfate in the M-CFO/FeS2/Na2S2O8/Vis system were determined. The variation of catalytic performance as a function of pH was also investigated. The degradation mechanism studies assisted by ESR technique and heterojunction structure analysis confirmed the Z-type heterojunction formation and generation of sulfate as well as superoxide free radicals, which played the main species responsible of TC degradation.

Significantly enhanced photocatalytic performance of the W-Zr-MOF-NH2@TpTt-COF heterostructure for tetracycline removal by defects engineering

A hollow heterojunction of W-Zr-MOF-NH2@TpTt-COF (WZT) was fabricated by combining etched W-Zr-MOF-NH2 with TpTt-COF. WZT, synthesized through acid etching and hydrothermal methods, showed better tetracycline degradation than pure W-Zr-MOF-NH2 and pure TpTt-COF due to its larger specific surface area and more active sites. The surface of WZT contains abundant oxygen vacancies (OVs) that capture electrons, promoting the separation of photogenerated e--h+ pairs and increasing WZT’s photocatalytic activity. WZT (1:1, mass) showed 87% degradation of tetracycline under 300 W Xenon lamp irradiation. The results of cycling experiments demonstrated the high stability and reusability of WZT (1:1), making it feasible for production. The excellent photocatalytic degradation of tetracycline by WZT (1:1) originates from the formation of heterojunctions and the presence of surface OVs, which reduces the strong photogenerated e--h+ complexation efficiency. Possible photocatalytic degradation mechanisms are proposed while demonstrating the formation of Z-scheme heterojunction in WZT, which aligned with the experimental results of electron spin resonance (ESR). The tetracycline oxidative decomposition process involves the participation of •OH, 1O2, •O2-, e-, and h+ as proven by ESR and radical trapping experiments. This work proposes a research idea to prepare high-performance photocatalysts with MOF@COF type, featuring OVs-rich and Z-scheme heterojunctions.

Microwave-assisted fabrication of 1D/2D CeO2/Bi2MoO6 heterojunction for efficient photocatalytic CO2 reduction to CH3OH

Photocatalytic CO2 reduction to fuels via visible light is regarded as a highly promising sustainable technology to address resource depletion and environmental apprehensions. However, the elevation of photocatalytic performance is limited due to some drawbacks of isolated catalysts such as poor CO2 adsorption performance, inadequate utilization of visible light, and rapid recombination of photo-generated carriers. Herein, a series of novel heterojunction catalysts, 1D/2D CeO2/Bi2MoO6 (CBMO-X), were fabricated utilizing the microwave-assisted method for the photocatalytic reduction of CO2. The CH3OH yield of the optimized CBMO-10 composite material reached 4.31 μmol⋅g−1⋅h−1 with excellent stability and structural integrity. Through a series of characterizations, it was found that the introduced CeO2 nanorods served as bifunctional sites for CO2 adsorption and photoelectron accumulation, effectively promoting CO2 conversion under visible light. In addition, CBMO-X exhibited faster photo-generated carriers migration rate due to the formation of the II-scheme heterojunction, which improved the photocatalytic performance obviously. Furthermore, the density functional theory (DFT) calculations and in situ XPS were used to investigate the carrier migration paths on the surface of composite materials. This work provided a novel strategy for the design of photocatalysts for efficient CO2 conversion.

Constructing cuprous oxide-modified zinc tetraphenylporphyrin ultrathin nanosheets heterojunction for enhanced photocatalytic carbon dioxide reduction to methane

The application of supermolecular naonostructures in the photocatalytic carbon dioxide reduction reaction (CO2RR) has attracted increasing attentions. However, it still faces significant challenges, such as low selectivity for multi-electron products and poor stability. Here, the cuprous oxide (Cu2O)-modified zinc tetraphenylporphyrin ultrathin nanosheets (ZnTPP NSs) are successfully constructed through the aqueous chemical reaction. Comprehensive characterizations confirm the formation of type-II heterojunction between Cu2O and ZnTPP in Cu2O@ZnTPP, and the electron transfer from Cu2O to ZnTPP through the Zn-O-Cu bond under the static contact. Under the visible-light irradiation (λ > 420 nm), the optimized Cu2O@ZnTPP sample as catalyst for photocatalytic CO2RR exhibits the methane (CH4) evolution rate of 120.9 μmol/g/h, which is ∼ 4 and ∼ 10 times those of individual ZnTPP NSs (28.0 μmol/g/h) and Cu2O (12.8 μmol/g/h), respectively. Meanwhile, the CH4 selectivity of ∼ 98.7 % and excellent stability can be achieved. Further experiments reveal that Cu2O@ZnTPP has higher photocatalytic conversion efficiency than Cu2O and ZnTPP NSs, and the photoinduced electron transfer from ZnTPP to Cu2O can be identified via the path of ZnTPP→ (ZnTPP•ZnTPP)*→ ZnTPP-→ Zn-O-Cu → Cu2O. Consequently, Cu2O@ZnTPP exhibits a shorter electron-hole separation lifetime (3.3 vs. 9.3 ps) and a longer recombination lifetime (23.1 vs. 13.4 ps) than individual ZnTPP NSs. This work provides a strategy to construct the organic nanostructures for photocatalytic CO2RR to multi-electron products.

Gadolinium modified g-C3N4 for S-Scheme heterojunction with monoclinic-WO3: Insights from DFT studies and related charge carrier dynamics

Modifying the surface structures of g-C3N4 through interfacial coupling with other semiconductors has been spotlighted as an efficient approach for improving photocatalytic efficiency. With the surge of S-scheme heterojunctions, the research is intensified towards designing this kind of composite for energy-environmental-related applications. In this context, a new approach involving surface modifications of g-C3N4 through Gd species and integrating with monoclinic-WO3 via a wet chemical approach to form S-scheme heterojunctions is investigated. The characterization results attested that the adopted protocol promotes the better dispersion of Gd species over the g-C3N4 surface and rigidly integrates with WO3. The optical response of the composite spanned a significant portion of the visible region in the solar spectrum. The computational studies and the findings of the Mott-Schottky plot collectively suggested that the position of band edges qualifies for the formation of S-scheme heterojunction. The results derived from photocurrent response measurements and photoluminescence technique attribute to the effective charge carrier separation in the heterostructure. The rate constant of Gd-g-C3N4/WO3 was 1.48 × 10−2 min−1 which was approximately 4.35 and 2.27 times greater than that of WO3 (0.34 × 10−2 min−1) and g-C3N4/WO3 (0.65 × 10−2 min−1) respectively. Furthermore, RhB degradation in the presence of scavengers validated the participation of superoxide and hydroxyl radicals in the degradation mechanisms. This was possible only when the conduction band electrons of WO3 recombined with the valence band holes of Gd-modified g-C3N4. The present work helps to understand the S-scheme heterojunction formation between surface-modified g-C3N4 and metal oxides and retain the involvement of energetic charge carriers in the desired redox reactions.

Interfacial oxygen vacancy engineering and built-in electric field mediated Z-scheme In2O3/Ag3PO4 heterojunction for boosted photocatalytic doxycycline degradation

Doxycycline pollutants in environment seriously destroy the balance of ecological system. A Z-scheme In2O3/Ag3PO4 heterojunction is constructed by attaching Ag3PO4 nanoparticles on hollow In2O3 hexagonal prism structures for efficient degradation of doxycycline. The doxycycline (30 mg/L) removal rate by IAO-1 (mole ratio of In2O3:Ag3PO4 is 1:3, 1.0 g/L) reaches 99.7% under visible light irradiation. Degradation rates are almost unchanged after five cycles of degradation experiments, demonstrating the excellent reusability and stability of the IAO-1 photocatalyst. The photocatalytic degradation of doxycycline in different water matrices by IAO-1 shows excellent performance, which provides significant potential for practical applications. The experiments and DFT results demonstrate that the built-in electric fields in IAO-1 contribute to the charge transfer from Ag3PO4 to In2O3, leading to the formation of a Z-scheme heterojunction with high redox capacity. The hollow defect structure of IAO-1 effectively activates molecular oxygen to generate oxygen vacancies and induce 1O2 production through energy transfer, which promotes the attack of benzene rings and oxygen-containing groups in the molecular structure of doxycycline, leading to hydroxylation, demethylation, and ring-opening reactions. This work provides new ideas for constructing Z-scheme photocatalysts with oxygen vacancies and built-in electric fields for practical wastewater treatment.

One-Step Preparation of High-Stability CsPbX3/CsPb2X5 Composite Microplates with Tunable Emission.

The core-shell structure is an effective means to improve the stability and optoelectronic properties of cesium lead halide (CsPbX3 (X = Cl, Br, I)) perovskite quantum dots (QDs). However, confined by the ionic radius differences, developing a core-shell packaging strategy suitable for the entire CsPbX3 system remains a challenge. In this study, we introduce an optimized hot-injection method for the epitaxial growth of the CsPb2X5 substrate on CsPbX3 surfaces, achieved by precisely controlling the reaction time and the ratio of lead halide precursors. The synthesized CsPbX3/CsPb2X5 composite microplates exhibit an emission light spectrum that covers the entire visible range. Crystallographic analyses and density functional theory (DFT) calculations reveal a minimal lattice mismatch between the (002) plane of CsPb2X5 and the (10) plane of CsPbX3, facilitating the formation of high-quality type-I heterojunctions. Furthermore, introducing Cl- and I- significantly alters the surface energy of CsPb2X5's (110) plane, leading to an evolutionary morphological shift of grains from circular to square microplates. Benefiting from the passivation of CsPb2X5, the composites exhibit enhanced optical properties and stability. Subsequently, the white light-emitting diode prepared using the CsPbX3/CsPb2X5 composite microplates has a high luminescence efficiency of 136.76 lm/W and the PL intensity decays by only 3.6% after 24 h of continuous operation.

Unlocking photocatalytic NO removal potential in an S‐type UiO‐66‐NH2/ZnS(en)0.5 heterostructure

AbstractThe contamination of nitric oxide presents a significant environmental challenge, necessitating the development of efficient photocatalysts for remediation. Conventional heterojunctions encounter obstacles such as large contact barriers, sluggish charge transport, and compromised redox capacity. Here, we introduce an innovative S‐type heterostructure photocatalyst, UiO‐66‐NH2/ZnS(en)0.5, designed specifically to overcome these challenges. The synthesis, employing a unique microwave solvothermal method, strategically aligns the lowest unoccupied molecular orbital of UiO‐66‐NH2 with the highest occupied molecular orbital of ZnS(en)0.5, fostering the formation of a stepped heterojunction. The resulting intimate interface contact generates a built‐in electric field, facilitating charge separation and migration, as evidenced by time‐resolved photoluminescence spectroscopy and photoelectrochemical tests. The abundant active sites in the porous UiO‐66‐NH2 counterpart provide adsorption and activation sites for nitrogen monoxide (NO) oxidation. Performance evaluation reveals exceptional photocatalytic NO removal, achieving 70% efficiency and 99% selectivity toward nitrates under simulated solar illumination. Evidence from X‐ray photoelectron spectroscopy and trapping experiments supports the effectiveness of the S‐type heterostructure, showcasing refined reactive oxygen species, particularly superoxide. Thus, this study introduces a new perspective on advanced NO oxidation and unlocks the potential of S‐scheme heterojunctions to refine reactive oxygen species for NO remediation.

S-scheme heterojunction Cu-porphyrin/TiO2 nanosheets with highly efficient photocatalytic reduction of CO2 in ambient air

Directly capturing CO2 in ambient air and converting it into value-added fuels using photocatalysis is a potentially valuable technology. In this study, Cu-porphyrin (tetrakis-carboxyphenyl porphyrin copper, CuTCPP) was innovatively anchored on the surface of TiO2 (titanium dioxide) nanosheets to form an S-scheme heterojunction. Based on this, a photocatalytic reaction system for stably converting CO2 in ambient air into value-added fuels at the gas–solid interface was constructed without addition of sacrificial agents and alkaline liquids. Under the illumination of visible light and sunlight, the evolution rate of CO is 56 μmol·g−1·h−1 and 73 μmol·g−1·h−1, respectively, with a potential CO2 conversion rate of 35.8 % and 50.4 %. The enhanced of photocatalytic performance is attributed to the introduction of CuTCPP, which provides additional active sites, significantly improves capture capacity of CO2 and the utilization of electrons. Additionally, the formation of S-scheme heterojunction expands the redox range and improves the separation efficiency of photo-generated charges.

Rapid preparation of AlFeO3/ZnO bulk heterojunctions through jet milling for photoelectrochemical water splitting

The investigation of photocatalytic behavior of compounds consisting of earth-abundant elements is vital for discovering cheap photocatalysts/photoelectrocatalysts. AlFeO3 is an attractive material in this context because all its constituent elements are earth-abundant. In this work, bulk heterojunctions (heterojunctions distributed throughout the volume of powder) of AlFeO3 and ZnO were prepared using the technique of jet milling and subsequently used for photoelectrochemical water splitting. Jet milling achieved two objectives – reduction of particle size and formation of heterojunctions. Jet milling of AlFeO3 and ZnO particles was performed under a nitrogen atmosphere to produce AlFeO3/ZnO heterojunctions. Making heterojunctions by using jet milling is extremely rapid, a single jet milling operation taking only five to ten minutes. The heterojunction powder sample exhibited a current density of 34.25 mA/cm2 under illumination (at 1.5 V vs. Ag/AgCl) when it was used as the working electrode in a three-electrode electrochemical cell for Oxygen Evolution Reaction (OER). In contrast, ZnO nanoparticles prepared by jet milling (under nitrogen atmosphere) exhibited a current density of 18.54 mA/cm2 under illumination (at 1.5 V vs. Ag/AgCl). Thus, AlFeO3/ZnO bulk heterojunctions showed a superior photoelectrochemical (PEC) performance as compared to ZnO nanoparticles.

Ag nanofilm enhanced S-type Ag@AgCl/tubular g-C3N4/Ti photoanode visible light response photocatalytic fuel cell

In this study, based on Ag@AgCl/tubular g-C3N4 (Ag@AgCl/TCN) composite, Ag nanoparticles were deposited on its surface to form Ag nanofilm enhanced composite through photoreduction of excessive silver nitrate solution to obtain Ag nanofilm Ag@AgCl/TCN photocatalyst. Finally, Ag nanofilm Ag@AgCl/TCN/Ti photoanode was successfully prepared by silica-sol drop-coating method, and assembled with Cu2O/Cu cathode to construct a photocatalytic fuel cell (PFC). Ag nanofilm can not only enhance the light absorption and utilization of Ag@AgCl/TCN/Ti, but also extend its light response wavelength to visible light, and be used as an electron transfer medium to reduce internal resistance. The photocurrent density and the photoconversion efficiency of the Ag nanofilm/Ag@AgCl/TCN/Ti are 8.01 mA·cm−2 and 1.24%, respectively, which are 2.49 and 2.54 times those of the Ag@AgCl/TCN/Ti photoanode, respectively. The first-order kinetic constant and the maximum power density of the Ag nanofilm-coated Ag@AgCl/TCN/Ti-Cu2O/Cu PFC system are 0.064 min−1 and 46.37 μW·cm−2, respectively, which are 1.39 and 1.94 times those of the Ag@AgCl/TCN-Cu2O/Cu PFC system, respectively. In addition, it degraded more than 95% of rhodamine B, 72.68% of tetracycline and 54.25% of bisphenol A within 60 min. The excellent performance of Ag nanofilm/Ag@AgCl/TCN/Ti-Cu2O/Cu is due to the strengthening of Ag nanofilm and the formation of S-type heterojunctions between AgCl and TCN. Free radicals (•Cl, h+, •OH, •O2-) and non-radicals (1O2) are involved in the degradation reaction of RhB degradation. It is worth noting that 6% Ag nanofilm/Ag@AgCl/TCN/Ti-Cu2O/Cu has a positive effect on the production of •O2-, and its output is approximately 1.89 times that of the Ag@AgCl/TCN/Ti-Cu2O/Cu. A series of material characterization experiments have been completed and possible mechanisms of operation have been proposed. This study provides a new scheme for the design and preparation of high-efficiency photoanode of PFC.

An organic/inorganic Z-scheme heterojunction Yb-MOF/BiOBr for efficient photocatalytic removal of NO

The advantages of visible light-driven catalysts with good light absorption, fast charge separation rate and high redox capacity are compelling. However, conventional inorganic semiconductor, such as pure BiOBr (BOB), showed a rapid photogenerated carriers recombination rate and low solar energy utilization ability, which limited the practical application of its photocatalytic performance. In this work, a novel organic/inorganic interleaved (Z-scheme) heterojunction Yb-MOF/BiOBr (Yb-MOF/BOB) photocatalyst was successfully synthesized. Compared with a single component, the Yb-MOF/BOB heterojunction exhibited significantly enhanced performance in photocatalytic oxidation of NO under visible light. Among them, Yb-MOF/BOB-20 had the best photocatalytic NO removal effect, up to 6424 ppb/g, which was 2.8 times and 4.2 times that of BOB and Yb-MOF, respectively. Photoelectrochemical characterization confirmed that the formation of heterojunctions broadened the absorption sidebands and increased the charge transfer at the interfacial junction of Yb-MOF/BOB. Combined with UPS, ESR and in-situ DRIFTS analysis, possible photocatalytic mechanisms were revealed, in which the formation of the Yb-MOF/BOB heterostructure endowed its high charge mobility and strong redox ability. Therefore, this work provided an effective way for photocatalytic removal of NO, and offered new ideas for developing heterogeneous photocatalysts.

Comparative study of interfacial charge transfer at the junction between CuInS2:In2S3/g-C3N4 photocatalysts for sacrificial hydrogen evolution activity

The quest for sustainable and efficient renewable energy sources has escalated in recent years, with photocatalytic hydrogen production gaining prominence due to its potential to harness solar energy for clean fuel generation. In this study, we design 2D/2D heterostructure CuInS2:In2S3/g-C3N4 nanosheets utilizing electrostatic interaction for hydrogen evolution reaction under visible light irradiation. Integrating CuInS2:In2S3 and g-C3N4 layers to form an interfacial 2D:2D heterostructure results in a broad light absorption range, effective charge separation, and excellent stability. The heterostructure ensures efficient interfacial charge transfer pathways, mitigating electron-hole recombination and promoting hydrogen evolution. The hybrid nanosheets prepared with the hydrothermal method exhibited ∼40-fold synergistic enhancement in hydrogen production and long-term stability. The synergistic boost in activity resulted from the formation of S-scheme heterojunctions (CuInS2/g-C3N4 and CuInS2/In2S3) within hybrid nanosheets.