The demand for less toxic, less expensive, and low operating temperature-based sensors to enhance detection of NO2 leaks is driven by the growing concern over the hazardous impacts in many sectors. The superiority of layered structures and its better carrier transport is more desirable in gas sensors. The α-MoO3 is a rapidly developing hotspot material in the field of gas sensing due to its distinctive layered structure, accessibility, and environmental friendliness. Herein, α-MoO3 nano-ribbons (NRs) with increased carrier transport through oxygen vacancies (Vo) was achieved by Cu-doping. Interestingly, Vo and carrier concentration (n) enhanced in Cu-doped α-MoO3 NRs. Due to synergistic enhancements in mobility (μH ∼ 1.85 cm−2V−1s−1), diffusion coefficient (Dn ∼ 7.05 m2s−1) and n ∼ 6.07 × 1019, the Cu-doped (4 at%) α-MoO3 NRs selectively displayed an ultra-high response of 715% for 10 ppm of NO2 at an operating temperature of 170 ℃. Further, it showed high response (161%) for 10 ppm at 110 ℃. The ensuing low limit of detection (LOD) (∼18 ppb), repeatability (4 cycles), high selectivity among H2S, SO2, & NH3, and stability over 100 days revealed excellent activity for NO2 detection. This work offers promising strategy for the fabrication of MoO3 NRs that are adaptable for NO2 sensing. #gassensors #fmed #srmist @FMEDSRMIST @SRMUniversityKtr @sciencedirect

Engineering non-Pt-based counter electrode is an essential step toward the commercialization of DSSC. Here, we have employed MoO3 rods as a counter electrode and improved its catalytic performance towards the reduction of 3I− to I3− by embedding MoS2 on it. This combination of nanostructures composed of MoO3 rods/MoS2 sheets possessed increased surface area for electrolyte interaction by roughly 3-fold and displayed an enhanced catalytic activity. MoS2's presence lowered the charge transport resistance of MoO3 by eleven folds. Both the limiting and exchange current density were increased roughly 6 –fold. A maximum power conversion efficiency of 3.9% was achieved by M/MS2 CE, which is 2-fold higher than the efficiency obtained using MoO3 CE. This work ascertains MoO3/MoS2 counter electrode as a potential candidate for a non-Pt-based CE and thereby helps reduce the cost of DSSCs to promote commercialization. #fmed #srmist @FMEDSRMIST @SRMUniversityKtr #couterelectrode #solar #dssc

We report a heterostructure photocathode composed of the optimal gradient of nickel cobalt disulphide layers (NiCo2S4 NS) over a p-Si nanowire (Si NW) surface designed for the solar-assisted water reduction process. The optimal Si NW/NiCo2S4 NS heterostructure exhibits enriched solar water reduction activity with a photocurrent density of 15 mA cm−2 at −0.8 V vs. RHE applied bias and an onset potential of 301 mV vs. RHE under simulated solar irradiation. Moreover, the fabricated heterostructure photocathode (Si NW/NiCo2S4 NS) at the applied bias of −0.3 V vs. RHE produces a hydrogen gas evolution rate of around 53.75 μmol cm−2 h−1. The accomplished catalytic activity of the heterostructure can be attributed to the HER electrocatalyst properties of NiCo2S4 as an interfacial layer, such as interfacial energies, charge transfer kinetics, and solar-driven water reduction activity at the photocathode/electrolyte interface. An electrochemical impedance spectroscopy study demonstrates a significant reduction in charge transfer resistance that results in rapid electron transfer at the interface for efficient charge separation and migration processes. The density functional theory calculations reveal that NiCo2S4 NS has a suitable electronic band alignment with a water redox potential advancing the catalytic efficiency owing to barrier-free electron transport with near-zero Gibbs free energy of hydrogen adsorption on hetero-interface sites (ΔGH* = 0.02 eV at Co1 site). Consequently, the proposed heterostructure scheme is a promising strategy for designing a high-performance Si photocathode for solar water reduction. @FMEDSRMIST @SRMUniversityKtr #solar #FMED

Recently, nanostructured tungsten oxide-based materials have received much attention in the field of the gas sensor due to their superior size-dependent gas adsorption and catalytic properties. Herewith, we have successfully prepared pure and Ag-doped WO3 nanostructures via a hydrothermal method. The effect of doping (Ag) in WO3 and their gas sensing properties was systematically studied. Interestingly, the Ag-2 sensor revealed the enhanced gas sensing response of 52404% @1000 ppb, which is 5-fold higher than that of the pure WO3 sample at 150 ℃. Moreover, Ag-2 sensor possessed an ultra-fast response and recovery time of 1 s and 3.5 s. Further, as-prepared sensors exhibit excellent selectivity, repeatability, and long-term stability. In addition, the DFT calculations were performed to evaluate the adsorption and charge transfer dynamics of NH3, H2S, and NO2 gas molecules on pure and Ag-doped WO3 surfaces. These results pave the new pathway to developing real-time metal oxide-based gas sensors at lower operating temperatures. #srmist #fmed #sensors #Ag #WO3

Bismuth Selenide is a Tellurium free topological insulator in V-VI compounds with an excellent thermoelectric performance from room temperature to mid-temperature region. Herein, hydrothermally prepared polycrystalline Bi2AgxSe3 nanostructures have been reported for thermoelectric application. The reduced lattice thermal conductivity and enhanced electrical transport properties synergistically boost the thermoelectric properties through the highly-dense stacking faults with the presence of dislocations. The IFFT (Inverse Fast Fourier Transform) pattern reveals the existence of stacking faults and dislocations. These highly dense stacking faults and dislocations act as active phonon scattering centers, which can contribute to effective phonon scattering results in extremely low lattice thermal conduction of 0.3 W/mK at 543 K. On the other hand, the involvement of phonon–phonon scattering primarily reduced the lattice thermal conductivity at elevated temperatures. In addition, phonon-carrier scattering was less compared to phonon–phonon scattering at elevated temperature region. Moreover, the enhancement of electrical conductivity and controlled reduction of the Seebeck coefficient plays a vital role in achieving the maximum power factor of 335 μW/mK2 at 543 K due to the energy filtering effect. The synergistic combination of low thermal conduction and the maximum power factor helps to achieve the high peak zT of 0.3 at 543 K. #thermoelectric #energyconservation #energy #bismuth #selenium #FMED #srmist

The design and construction of state-of-the-art wearable thermoelectric materials are important for the development of self-powered wearable thermoelectric generators (WTEGs). Molybdenum disulfide (MoS2) has been reported as a noteworthy thermoelectric (TE) material because of its large intrinsic bandgap and high carrier mobility. In this work, Cu-doped two-dimensional layered MoS2 nanosheets were grown on carbon fabric (CF) via a hydrothermal method. The electrical conductivity, Seebeck coefficient, and power factor for the Cu-doped MoS2 were found to increase with increasing temperature. The maximum Seebeck coefficient was obtained for a MoS2 sample doped with 4 at% of Cu (CM4) was ∼10 μV/K at 303 K and ∼13 μV/K at 373 K. The enhancement in the Seebeck coefficient was attributed to an energy-filtering effect caused by the interfacial barrier between MoS2 and Cu. In addition, a thermoelectric device was designed with four pairs of TE materials, where CM4 (4 at%) was used as a p-type material and Cu wire was used as an n-type material. These p- and n-type materials were connected electrically in series and thermally in parallel to generate a voltage of 190.7 μV at a temperature gradient of 8 K.

We report on the thermoelectric properties of few-layer MoS2 fabricated on 290 nm-SiO2/Si by a two-zone atmospheric pressure chemical vapor deposition (CVD) technique. The decoupling of electrical conductivity and Seebeck coefficient is noticed after 592 K, where the electrical conductivity (σ) is linearly increased and the Seebeck coefficient (S) is exponentially increased. The highest values of σ and S are 10.9 S cm^−1 and 10312 nV K^−1 at 734 K, respectively, and the highest power factor (S^2 σ) is 116 nW m^−1 K^−2 at 734 K. The calculated out-plane (A1g) displacement and the decreased A1g phonon lifetime are revealing the reduced phonon transport. The current investigations paved an attention to decouple the thermoelectric properties of few layer MoS2.