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1.
J Colloid Interface Sci ; 675: 471-480, 2024 Jul 06.
Artículo en Inglés | MEDLINE | ID: mdl-38986320

RESUMEN

In addition to the intrinsic driving force of photocatalysis, the external thermal field from the photothermal effect can provide additional energy to the photo-catalytic system to improve the photo-catalytic hydrogen-evolution (PHE) efficiency. Herein, based on the results of density functional theory, we designed and constructed a hollow core-shell FeNi2S4@Mn0.3Cd0.7S (NFS@MCS) S-scheme heterojunction with a photothermal effect, thereby realising a significant enhancement of the PHE performance due to the thermal effect, S-scheme heterojunction and hollow core-shell morphology. As a light collector and heat source, the hollow NFS could absorb and convert photons into heat, resulting in the increased local temperature of photocatalyst particles. Moreover, the S-scheme charge path at the interface not only improved the carrier separation efficiency but also retained a higher redox potential. All these are favourable to increase the PHE activity. The PHE tests show that 0.5 %-NFS@MCS exhibits the highest PHE rate of 17.11 mmol·g-1·h-1, 7.7 times that of MCS. Moreover, through a combination of theoretical calculation and experimental evidence, the PHE mechanism of the NFS@MCS system is discussed and clarified in-depth.

2.
J Colloid Interface Sci ; 673: 463-474, 2024 Jun 13.
Artículo en Inglés | MEDLINE | ID: mdl-38878380

RESUMEN

Rational design of the morphology and heterojunction to accelerate the separation of electron-hole pairs has played an indispensable role in improving the photocatalytic hydrogen evolution. ZnIn2S4 (ZIS) has aroused considerable attention in solar-to-chemical energy conversion due to its remarkable photoelectrical properties and relatively negative energy band, whereas it still suffers from the severe photogenerated carrier recombination and catalyst aggregation. Herein, guided by density functional theory calculations, the constructed FeSe2@ZnIn2S4 (FS@ZIS) heterojunction model has a hydrogen Gibbs free energy closer to zero compared with pure ZIS and FS, which is beneficial for hydrogen adsorption and desorption on the photocatalyst surface. Therefore, a novel cross-like core-shell FS@ZIS Step-scheme (S-scheme) heterojunction was synthesized successfully by in-situ growing ZIS nanosheets on the surface of cross-like FS. The structure with cross-like core-shell morphology not only inhibits the agglomeration of ZIS to increase specific surface area, but also provides a tight interface with S-scheme heterojunction. Moreover, the S-scheme heterojunction with a tight interface can effectively separate electron-hole pairs, leaving photoinduced charges with higher potentials. Furthermore, FS@ZIS-20 possesses exceptional photothermal capabilities, enabling the conversion of optical energy from visible and near infrared light to heat, thereby further enhancing the photocatalysis reaction. As a result, the cross-like core-shell FS@ZIS S-scheme heterojunction exhibits an excellent photocatalytic hydrogen evolution rate (7.640 mmol g-1 h-1), which is 24 times higher than that of pure ZIS (0.319 mmol g-1 h-1) under visible and near infrared light. Furthermore, employing more in-depth density functional theory calculations further investigates the charge transfer pathway of the FS@ZIS S-scheme heterojunction. This work provides insights into the construction of S-scheme heterojunctions with core-shell structure and photothermal effect for photocatalytic evolution hydrogen.

3.
Dalton Trans ; 53(13): 6041-6049, 2024 Mar 26.
Artículo en Inglés | MEDLINE | ID: mdl-38470841

RESUMEN

Exploiting effective, stable, and cost-efficient electrocatalysts for the water oxidation reaction is highly desirable for renewable energy conversion techniques. Constructional design and compositional manipulation are widely used approaches to efficaciously boost the electrocatalytic performance. Herein, we designed a NiFe-bimetallic sulfide/N-doped carbon composite via a two-step thermal treatment of Prussian blue analogues/cellulose nanofibers (PBA/CNFs) film. The NiFe-bimetallic sulfide/N-doped carbon composite displayed enhanced OER performance in an alkaline environment, with an overpotential of 282 mV at 10 mA cm-2, a Tafel slope of 59.71 mV dec-1, and good stability, making the composite a candidate electrocatalyst for OER-related energy equipment. The introduction of CNFs in the precursor prevented the aggregation of PBA nanoparticles (NPs), exposed more active sites, and the resulting carbon substrate enhanced the electroconductivity of the composite. Moreover, the synergistic effect of Ni and Fe in the bimetallic sulfide could modulate the configuration of electrons, enrich the catalytically active sites, and augment the electric conductivity, thus ameliorating the OER performance. This study broadens the application of MOF-CNF composites to construct hierarchical structures of metal compounds and provides some thoughts for the development of cost-effective precious-metal-free catalysts for electrocatalysis.

4.
J Colloid Interface Sci ; 662: 276-288, 2024 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-38354555

RESUMEN

An emerging approach that employs both light and vibration energy on binary photo-/piezoelectric semiconductor materials for efficient hydrogen (H2) evolution has garnered considerable attention. ZnIn2S4 (ZIS) is recognized as a promising visible-light-activated photocatalyst. However, its effectiveness is constraint by the slow separation dynamics of photoexcited carriers. Density functional theory (DFT) predictions have shown that the integration of piezoelectric BiFeO3 (BFO) is conducive to the reduction of the H2 adsorption free energy (ΔGH*) for the photocatalytic H2 evolution reaction, thereby enhancing the reaction kinetics. Informed by theoretical predictions, piezoelectric BFO polyhedron particles were successfully synthesized and incorporated with ZIS nanoflowers to create a ZIS/BFO heterojunction using an ultrasonic-assisted calcination method. When subjected to simultaneous ultrasonic treatment and visible-light irradiation, the optimal ZIS/BFO piezoelectric enhanced (piezo-enhanced) heterojunction exhibited a piezoelectric photocatalytic (piezo-photocatalytic) H2 evolution rate approximately 6.6 times higher than that of pristine ZIS and about 3.0 times greater than the rate achieved under light-only conditions. Moreover, based on theoretical predictions and experimental results, a plausible mechanism and charge transfer route for the enhancement of piezo-photocatalytic performance were studied by the subsequent piezoelectric force microscopy (PFM) measurements and DFT calculations. The findings of this study strongly confirm that both the internal electric field of the step-scheme (S-Scheme) heterojunction and the alternating piezoelectric field generated by the vibration of BFO can enhance the transportation and separation of electron-hole pairs. This study presents a concept for the multipath utilization of light and vibrational energy to harness renewable energy from the environment.

5.
Small ; : e2311504, 2024 Feb 27.
Artículo en Inglés | MEDLINE | ID: mdl-38412431

RESUMEN

Herein, guided by the results of density functional theory prediction, the study rationally designs a hollow core-shell FeNi2 S4 @ZnIn2 S4 (FNS@ZIS) Step-scheme (S-scheme) heterojunction for photocatalytic H2 evolution with photothermal-assisted. The hollow FNS spheres offered substrate for coating the ZIS nanosheets, which can inhibit ZIS nanosheets from agglomerating into pellet, enrich the active site, increase specific surfaces, and raise the light absorption. Notably, due to its excellent photothermal properties, FNS core generated heat unceasingly inside under visible-light irradiation and effectively prevent the heat loss of the reaction system, which increased the local temperature of photocatalysts and thus accelerated the charge migration. In addition, the S-scheme heterojunction construction via in situ growth has a tight interface, which can facilitate the separation and transfer of carriers and achieve high redox potential. Owning to the distinctive construction, the hollow core-shell FNS@ZIS S-scheme heterojunction show extraordinary stability and photocatalytic H2 evolution rate with 7.7 mmol h-1  g-1 , which is ≈15.2-fold than pristine ZIS. Based on the double evidence of theoretical predictions and experimental confirmations, the photothermal effect and electron transfer mechanism of this innovative material are investigated in depth by the following infrared thermography technology and deep DFT calculations.

6.
J Colloid Interface Sci ; 657: 672-683, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38071816

RESUMEN

Suppressing the electron-hole recombination rate of catalyst legitimately is one of the effective strategies to improve photocatalytic hydrogen evolution. Herein, carbon-coated metal oxide, ZnFe2O4@C (ZFO@C), nanoparticles were synthesized and employed to couple with quadrupedal Cd0.9Zn0.1S (CZS) via an ordinary ultrasonic self-assembly method combined with calcination to form a novel ZFO@C/CZS catalyst with step-scheme (S-scheme) heterojunction. The photocatalytic hydrogen evolution reaction (HER) was conducted to verify the enhanced photoactivity of ZFO@C/CZS. The optimal ZFO@C/CZS exhibits an extraordinary photocatalytic HER rate of 111.3 ± 0.9 mmol g-1 h-1 under visible-light irradiation, corresponding to an apparent quantum efficiency as high as (76.2 ± 0.9)% at 450 nm. Additionally, the as-synthesized ZFO@C/CZS composite exhibits high stability and recyclability. The excellent photocatalytic hydrogen evolution performance should arise from the formed S-scheme heterojunction and the unique ZFO@C core-shell structure, which inhibit electron hole recombination as well as provide more reactive sites. The pathway of S-scheme charge transfer was validated through density functional theory calculations and electrochemical measurements. This work provides a rational strategy for the synthesis of unique magnetic S-scheme heterojunction photocatalysts for water splitting under visible light irradiation.

7.
Dalton Trans ; 52(41): 14956-14966, 2023 Oct 24.
Artículo en Inglés | MEDLINE | ID: mdl-37800910

RESUMEN

The development of efficient and economical photocatalysts is considered a promising strategy for pollution remediation. Magnetically separable SnIn4S8/ZnFe2O4 composites (SIS/ZFO) were prepared by combining SIS with ZFO. The composite with a 30% ZFO mass ratio (SIS/ZFO-30) was the most effective and achieved 60% removal of tetracycline (TC) in 120 min. It has a rate constant of 7.94 × 10-3 min-1, which is 6.3 and 27.2 times higher than those of pure SIS and pure ZFO, respectively. The improved photocatalytic performance can be attributed to the formation of S-scheme heterojunctions between SIS and ZFO, which results in the strong absorption of visible light, the enhanced separation of electron-hole pairs, and the higher redox ability of photoinduced charges. Additionally, SIS/ZFO composites have excellent magnetic properties and high stability, and the recovered samples still retained good photocatalytic degradation performances after four cycles of experiments. Thus, the coupling of SIS with ZFO provides a valuable strategy for enhancing photocatalytic potential and offers a promising pathway for water remediation.

8.
Chemosphere ; 340: 139777, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-37567276

RESUMEN

Reasonable design of heterojunction photocatalysts with high-quality interfacial coupling is an effective way to improve the photocatalytic activity of semiconductors. Herein, we successfully decorated Zinc indium sulfide (ZnIn2S4, ZIS) on perovskite Lanthanum ferrite (LaFeO3, LFO) with more active sites by a pre-hydrothermal combined post-calcination method, and constructed S-scheme heterojunction photocatalyst with a unique hollow corncob-like morphology for efficient photocatalytic hydrogen production and tetracycline (TC) degradation. When the mass ratio of LFO is 35% and 15%, the ZIS/LFO photocatalyst exhibits the best hydrogen evolution rate and TC photodegradation performance, respectively. Notably, the optimum hydrogen production rate is 6 times that of pure ZIS with excellent cycling stability. The enhanced photoactivity can be explained by the hollow corncob-like morphology and the formed S-scheme heterojunction with close interface contact between ZIS and LFO, which significantly improves the spatial separation and migration efficiency of photoexcited carriers, while maintaining a high redox potential. Finally, it provides an effective support for the photocatalytic mechanism through calculation results of density functional theory. This work not only provides a novel construction strategy of photocatalysts for efficient photocatalytic hydrogen evolution and organic pollutant degradation, but also opens up a new insight for perovskite-modified S-scheme heterojunction.


Asunto(s)
Compuestos Heterocíclicos , Zea mays , Agua , Tetraciclina , Antibacterianos , Hidrógeno
9.
J Colloid Interface Sci ; 650(Pt A): 825-835, 2023 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-37450971

RESUMEN

The reasonable design and fabrication of heterojunction could regulate the photocatalytic performance to some extent, yet it is still a great challenge to construct the S-scheme heterostructure with the stable as well as tight interface on the surface of semiconductor photocatalysts. Herein, the ZnIn2S4/Cu2MoS4 (ZIS/CMS) S-scheme heterostructure was fabricated by in-situ assembling ZIS nanosheets on the CMS plates, obtaining a mossy tile-like morphology. Owing to the compact interface resulting from in-situ growth, this unique architecture efficiently facilitated the separation and transfer of light-induced charges, guaranteed the larger interface area, and enriched the active sites for photocatalytic redox reactions. After adjusting the mass ratio of CMS in ZIS/CMS, S-scheme heterostructure exhibited the remarkable performance with an optimal H2 producing rate up to 1298 µmol·h-1 g-1, about 13.8 times than that of pristine ZIS. The mechanism and driving force of charge transfer and separation in S-scheme heterostructure photocatalysts were explained and discussed. This investigation will provide new insight into design and construction of S-scheme heterojunction photocatalysts for H2 evolution.

10.
J Colloid Interface Sci ; 644: 95-106, 2023 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-37094476

RESUMEN

The key to obtain effective photocatalysts is to increase the efficiency of light energy conversion, and thus the design and implementation of full-spectrum photocatalysts is a potential approach to solve this problem especially by extending the absorption range to near-infrared (NIR) light. Herein, the improved full-spectrum responsive CuWO4/BiOBr:Yb3+,Er3+ (CW/BYE) direct Z-scheme heterojunction was prepared. The CW/BYE with CW mass ratio of 5% had the best degradation performance, and the removal rate of tetracycline reached 93.9% in 60 min and 69.4% in 12 h under visible (Vis) and NIR light, respectively, which were 5.2 and 3.3 times of BYE. According to the outcome of experimental, the reasonable mechanism of improved photoactivity was put forward on the basis of (i) the up-conversion (UC) effect of Er3+ ion to convert NIR photon to ultraviolet or visible light, which can be used by CW and BYE, (ii) the photothermal effect of CW to absorb the NIR light, increasing the local temperature of photocatalyst particle to accelerate the photoreaction, and (iii) the formed direct Z-scheme heterojunction between BYE and CW to boost the separation of photogenerated electron-hole pairs. Additionally, the excellent photostability of the photocatalyst was verified by cycle degradation experiments. This work opens up a promising technique for designing and synthesizing full-spectrum photocatalysts by utilizing synergetic effects of UC, photothermal effect and direct Z-scheme heterojunction.

11.
J Colloid Interface Sci ; 641: 26-35, 2023 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-36924543

RESUMEN

The construction of a p-n heterojunction structure is considered to be an effective method to improve the separation of electron-hole pairs in photocatalysts. A series of ZnIn2S4/CoFe2O4 (ZIS/CFO) photocatalysts with p-n heterojunctions were prepared via a method involving ultrasonication and calcination. The synthesized photocatalysts were tested and analyzed via various testing techniques, and their hydrogen evolution rates were evaluated. Compared with pure ZIS, ZIS/CFO with different mass ratios of CFO to ZIS showed improved photocatalytic hydrogen production performance, and the optimal photoactivity showed a nearly 12-fold increase, which can be attributed to the formation of p-n junctions and the formed internal electric field, accelerating the separation of electron-hole pairs and effectively improving the photocatalytic hydrogen evolution rate. The excellent stability of the ZIS/CFO composite was proven by three cycle experiments. In addition, the ZIS/CFO composite also possessed excellent magnetic properties to realize facial magnetic recoverability. This work paves the way for the design and preparation of magnetically recoverable p-n heterojunction photocatalysts.

12.
Nanotechnology ; 31(49): 495405, 2020 Dec 04.
Artículo en Inglés | MEDLINE | ID: mdl-32975224

RESUMEN

Bi metal attached BiOBr with oxygen defect (BiOBr(3)-Bi(x%, x = 10, 20, 30)) nanosheets was prepared via the hydrothermal process in this study. The different characterization techniques of x-ray diffraction, x-ray photoelectron spectrometer, electron spin resonance (ESR), field emission scanning electron microscope, and high resolution transmission electron microscope were used to distinguish the composition, crystal structure, and morphology of the samples. Under visible light irradiation, the BiOBr(3)-Bi(x%, x = 10, 20, 30) samples exhibited improved photocatalytic activity for the degradation of colored dyes (RhB) and colorless tetracycline hydrochloride. Such an improvement was ascribed to the widened visible light absorption and enhanced separation of the photogenerated electron-hole pairs because of the synergistic effect of oxygen vacancies and Bi metal with plasmon resonance effects. A possible photocatalytic mechanism of the quasi Z-scheme process was proposed on the basis of ESR measurements and radical-trapping experiments.

13.
Nanotechnology ; 31(30): 305701, 2020 Jul 24.
Artículo en Inglés | MEDLINE | ID: mdl-32272459

RESUMEN

Efficient and noble metal-free co-catalyst loading is an effective solution for separating and transferring photo-generated carriers and lowering the overpotential in photocatalytic H2 evolution activity. In this work, we designed and prepared a series of novel NiCoP/Mn0.3Cd0.7S (NCP/MCS) composites by modifying MCS nanorods with the co-catalyst NCP using a simple calcination method. Notably, the 10-NCP/MCS composite displays the optimum photocatalytic H2 evolution rate of 118.5 mmol g-1 h-1 under visible-light irradiation. This is approximately 3.39 times higher than that of pure MCS. The corresponding apparent quantum efficiency is 10.2% at 420 nm. The superior photocatalytic activity of the NCP/MCS composites can be attributed to the efficient separation of photogenerated carriers caused by the intimate heterojunction interface between NCP and MCS, smaller transfer resistance, and lower overpotential of NCP. Moreover, the NCP/MCS composites exhibit remarkable photostability. A plausible mechanism is proposed.

14.
Dalton Trans ; 49(19): 6259-6269, 2020 May 19.
Artículo en Inglés | MEDLINE | ID: mdl-32329479

RESUMEN

Development of noble-metal-free photocatalysts for efficient H2 production from sunlight-driven water-splitting has aroused great interest in recent years. Herein, unique Cd0.5Zn0.5S@ZnS core-shell nano-spheres decorated with Ni2P and g-C3N4 cocatalysts were prepared for the first time, and they are highly active and stable toward the visible-light-driven (λ > 420 nm) H2 evolution reaction (HER). Noticeably, the optimized Cd0.5Zn0.5S@ZnS-Ni2P/g-C3N4 with 50 wt% ZnS, 3 wt% Ni2P, and 8 wt% g-C3N4 (CZ0.5S@50ZS-3N/8CN) exhibits a superior HER activity of 55.43 mmol·g-1·h-1, approximately 25 and 18 times higher than those of CZ0.5S@50ZS and Pt-decorated CZ0.5S@50ZS (CZ0.5S@50ZS-Pt), respectively. Meanwhile, the corresponding apparent quantum yield (AQY) at 420 nm is as high as 21%. It is revealed that the protective ZnS shell on the CZ0.5S core enhances the photo-stability of the hybrid significantly. Moreover, the synergistic effect of the Ni2P and g-C3N4 cocatalysts leads to the effective transfer and separation of charge carriers. The results presented in this work may pave the way for the ingenious design and fabrication of highly active nano-structures for sufficient solar utilization.

15.
Nanotechnology ; 30(47): 475704, 2019 Nov 22.
Artículo en Inglés | MEDLINE | ID: mdl-31430737

RESUMEN

A novel direct Z-scheme Zn0.1Cd0.9S/FeWO4 (ZCS/FW) photocatalyst was prepared by a facile calcination method. The photocatalytic performance was investigated by photodegradation rhodamine B (RhB) and photocatalytic production hydrogen (H2) under visible light irradiation. Compared with the pure ZCS, the ZCS/FW composites show considerably improved photocatalytic activity for degradation RhB and production H2. Noticeably, the ZCS/FW with 7 wt% of FW exhibits optimal photocatalytic activity with the H2 evolution rate of 34.6 mmol g-1 h-1 and photodegradation of about 98% of RhB solution (10 mg l-1) in 60 min. These outstanding photocatalytic performances were found to be ascribed to the formation of direct Z-scheme heterojunction, resulting in effective separation and transfer of photogenerated charge carriers. Moreover, active species trapping experiments further demonstrate the electrons transfer followed Z-scheme system, and the photocatalytic mechanism was proposed.

16.
Nanotechnology ; 30(35): 355301, 2019 Aug 30.
Artículo en Inglés | MEDLINE | ID: mdl-31121572

RESUMEN

The aspect ratio and arrangement of nanowires play an important role in achieving excellent optoelectronic performance for metal nanowire-based transparent conductive films (TCFs). However, limited to the technology and material properties, studies are always focused on only one of the issues. Here, a novel strategy for manipulating the relative aspect ratio and arrangement of nickel nanowires (NiNWs) at nanoscale by Halbach array assisted assembly technology is introduced. Head-to-tail nickel nanowire chains as large as hundreds of micrometers are formed as a result of the dipole-dipole interactions of wire-wire. The arrangement of nickel nanowires can be preciously controlled by layer-by-layer deposition. Notably, the alignment create a significant improvement on the optoelectronic performance of nickel nanowire TCFs. The optimized orderly aligned NiNWs TCFs demonstrate super optoelectronic performance (90 Ω sq-1, 86%) than disordered NiNW TCFs (200 Ω sq-1, 80%). Moreover, NiNW-based TCFs exhibit outstanding long-term oxidation stability at 80 °C over 30 d as well as high-temperature oxidization stability even up to 300 °C, that is the most stable metal nanowire-based TCFs in air as far as we know. The low-cost, good optoelectronic performance and excellent oxidation resistance of aligned NiNWs will make them as attractive alternatives to silver nanowires for TCFs application.

17.
ChemSusChem ; 12(4): 795-800, 2019 Feb 21.
Artículo en Inglés | MEDLINE | ID: mdl-30628203

RESUMEN

Two-dimensional tungsten sulfide is widely applied in electrocatalysis. However, WS2 possesses catalytic active sites located at the layer edge and an inert surface for catalysis. Therefore, increasing the exposure of active sites at the edge and effectively activating the inert sites on the surface is an important challenge. Here, an edge/defect-rich and oxygen-heteroatom-doped WS2 (ED-O-WS2 ) superstructure was synthesized. The power-conversion efficiency (PCE) of dye-sensitized solar cells (DSCs) based on an ED-O-WS2 counter electrode reached 10.36 % (under 1 sun, AM 1.5, 100 mW cm-2 ) and 11.19 % (under 40 mW cm-2 ). These values are, to our knowledge, the highest reported efficiency for DSCs based on Pt-free counter electrodes in I3 - /I- electrolytes. Analysis of the micro/nano structure and the electrocatalytic mechanism indicate that ED-O-WS2 exhibits metallic properties in the electrolyte, and that abundant edges and defects as well as oxygen doping in ED-O-WS2 play an important role in improving the catalytic activity of WS2 . Moreover, ED-O-WS2 displays better catalytic reversibility for I3 - /I- electrolytes than Pt.

18.
ACS Omega ; 3(10): 13960-13966, 2018 Oct 31.
Artículo en Inglés | MEDLINE | ID: mdl-31458091

RESUMEN

Organic-inorganic hybrid material is a recent hot topic in the scientific community. The best band gap for the entire solar absorption spectrum is about 1.1 eV. However, the lead perovskite band gap is about 1.5 eV. Therefore, developing organic-inorganic hybrid material toward the broader light harvesting of the solar spectrum is extremely urgent. In this study, we prepare three kinds of organic-inorganic hybrid palladium perovskite materials, including (CH3NH3)2PdCl4, (CH3NH3)2PdCl4-x Br x , and CH3NH3PdI3, for an optoelectronic response. The absorption cut offs of (CH3NH3)2PdCl4, (CH3NH3)2PdCl4-x Br x , and CH3NH3PdI3 are approximately 600, 700, and 1000 nm, respectively. The band gaps of (CH3NH3)2PdCl4, (CH3NH3)2PdCl4-x Br x , and CH3NH3PdI3 are determined to be approximately 2.15, 1.87, and 1.25 eV, respectively. To the best of our knowledge, this is the first study that discusses adsorption properties and photoelectric behavior of organic-inorganic hybrid palladium perovskite materials. Interestingly, the photoelectric response of the devices based on CH3NH3PdI3 reaches 950 nm. The results will attract attention in the fields of optical recorders, optical memory, security, light capture, and light treatment.

19.
ACS Omega ; 3(9): 11009-11017, 2018 Sep 30.
Artículo en Inglés | MEDLINE | ID: mdl-31459211

RESUMEN

Splitting of water into hydrogen and oxygen has become a strategic research topic. In the two semi-reactions of water splitting, water oxidation is preferred to the four-electron-transfer process with a higher overpotential (η) and is the decisive step in water splitting. Therefore, efficient water oxidation catalysts must be developed. IrO x and RuO x catalysts are currently the most efficient catalysts in water oxidation. However, the limited reserve and high prices of precious metals, such as Ir and Ru, limit future large-scale industrial production of water oxidation catalysts. In this study, we tune inert Ni-foam into highly active NiOOH/FeOOH heterostructures as water oxidation catalysts via three-step strategy (surface acid-treating, electroplating, and electrooxidation). NiOOH/FeOOH heterostructures as water oxidation catalysts only require η of 257 mV to reach a current density of 10 mA cm-2, which is superior to that of IrO2/Ni-foam (280 mV). The high electrochemically active surface area (72.50 cm2) and roughness factor demonstrate abundant interfaces in NiOOH/FeOOH heterostructures, thus accelerating water oxidation activity. The small value (4.8 Ω cm2) of charge transfer resistance (R ct) indicate that fast electronic exchange occurs between NiOOH/FeOOH heterostructures catalyst and reaction of water oxidation. Hydrogen-to-oxygen volume ratios (approximately 2:1) indicate an almost overall water splitting by the double-electrode system. Faraday efficiency of H2 or O2 is close to 90% at 2:1 hydrogen-to-oxygen volume ratio. NiOOH/FeOOH heterostructures exhibit good stability. The results provide significance in fundamental research and practical applications in solar water splitting, artificial photoelectrochemical cells, and electrocatalysts.

20.
RSC Adv ; 8(36): 19958-19963, 2018 May 30.
Artículo en Inglés | MEDLINE | ID: mdl-35541684

RESUMEN

Organic-inorganic hybrid-based lead perovskites show inherent and unavoidable problems such as structural instability and toxicity. Therefore, developing low-cost and environment-friendly organic-inorganic hybrid materials is extremely urgent. In this study, we prepared earth-abundant and environment-friendly organic-inorganic hybrid tetrachloroferrate salt CH3NH3FeCl4 (MAFeCl4) for optoelectronic applications. The single crystal diffraction data are assigned to the orthorhombic MAFeCl4 (Pnma space group), with parameters a = 11.453 (5) Å, b = 7.332 (3) Å, c = 10.107 (5) Å, α = 90.000, ß = 90.000, and γ = 90.000. The band gap of MAFeCl4 is approximately 2.15 eV. Moreover, three-emission luminescence (398, 432 and 664 nm) was observed. To the best of our knowledge, this is the first study involving the investigation of the structure, adsorption properties and photoelectric behavior of MAFeCl4. A low cost photodetector based on the MAFeCl4 thin film is efficient under different monochromatic light from 330 nm to 410 nm with different chopping frequencies (1.33 Hz to 40 Hz). The photoelectric conversion efficiency based on FTO/TiO2/MAFeCl4/carbon electrode device reaches 0.054% (V oc = 319 mV, J sc = 0.375 mA cm-2, and fill factor = 0.45) under AM1.5, 100 mW cm-2 simulated illumination. Our findings will attract attention from the magnetic, piezoelectric and photoelectronic research fields.

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