ABSTRACT
Ternary Cu2SnS3 (CTS) is an attractive nontoxic and earth-abundant absorber material with suitable optoelectronic properties for cost-effective photoelectrochemical applications. Herein, we report the synthesis of high-quality CTS nanoparticles (NPs) using a low-cost facile hot injection route, which is a very simple and nontoxic synthesis method. The structural, morphological, optoelectronic, and photoelectrochemical (PEC) properties and heterojunction band alignment of the as-synthesized CTS NPs have been systematically characterized using various state-of-the-art experimental techniques and atomistic first-principles density functional theory (DFT) calculations. The phase-pure CTS NPs confirmed by X-ray diffraction (XRD) and Raman spectroscopy analyses have an optical band gap of 1.1 eV and exhibit a random distribution of uniform spherical particles with size of approximately 15-25 nm as determined from high-resolution transmission electron microscopy (HR-TEM) images. The CTS photocathode exhibits excellent photoelectrochemical properties with PCE of 0.55% (fill factor (FF) = 0.26 and open circuit voltage (Voc) = 0.54 V) and photocurrent density of -3.95 mA/cm2 under AM 1.5 illumination (100 mW/cm2). Additionally, the PEC activities of CdS and ZnS NPs are investigated as possible photoanodes to create a heterojunction with CTS to enhance the PEC activity. CdS is demonstrated to exhibit a higher current density than ZnS, indicating that it is a better photoanode material to form a heterojunction with CTS. Consistently, we predict a staggered type-II band alignment at the CTS/CdS interface with a small conduction band offset (CBO) of 0.08 eV compared to a straddling type-I band alignment at the CTS/ZnS interface with a CBO of 0.29 eV. The observed small CBO at the type-II band aligned CTS/CdS interface points to efficient charge carrier separation and transport across the interface, which are necessary to achieve enhanced PEC activity. The facile CTS synthesis, PEC measurements, and heterojunction band alignment results provide a promising approach for fabricating next-generation Cu-based light-absorbing materials for efficient photoelectrochemical applications.
ABSTRACT
An array of microneedles (MNs) of chitosan-graphene assembled in porous carbon (CS-GAPC) nanocomposites has been synthesized and evaluated. The safety of the formulated system has been ensured using detailed in vivo toxicological studies and efficacy has been ensured by evaluating the stimuli (pH and electric field) initiated drug delivery properties. Drug cephalexin has been incorporated in these MNs. In vivo toxicological studies of CS-GAPC nanocomposite were performed on Sprague rats, using acute dermal and subacute dermal (ADT& SADT) test, histopathological studies, biochemical studies, and AMES tests. ADT and SADT studies showed that median lethal dose (LD50 ) was found greater than 2000 mg/kg body weight; with no abnormal weight gain and food consumption, during the study period of 28 days. This study showed that administration of CS-GAPC did not cause any substantial alterations in hematological and biochemical parameters of the animals. Histopathological studies showed no significant changes in the control and CS-GAPC administered groups. AMES tests reveal that CS-GAPC nanocomposite is nonmutagenic against the Salmonella thyphimurium strains. No abnormalities were observed in the animal's chromosomal aberrations and clastogenic values when the animals were treated with CS-GAPC. At acidic pH of 4, the encapsulated drug was completely released, indicating that the drug release from the prepared nanocomposite is pH dependent. An electric field of 5 V showed optimum drug release, as a function of applied electric pulses. A biologically safe drug encapsulation model system is hence projected for smart drug delivery (pH dependent and electric field triggered) using the microneedle approach. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1582-1596, 2019.
