Publications

In this communication, we report a new method for effective immobilization of Ag nanoparticles (AgNPs) on thiolated singlestranded DNA (thiol-ssDNA) modified Au electrode (AuE) surface via coordination interactions between the nitrogen atoms of DNA bases and AgNPs. It suggests that the AgNP-immobilized AuE exhibits notable catalytic performance for H2O2 reduction and the loading of AgNPs on the AuE surface and therefore the effective catalytic area can be tuned by the immobilization time of thiol-ssDNA and adsorption time of AgNPs. This H2O2 sensor has a fast amperometric response time of less than 3 s and its linear range and detection limit are estimated to be from 0.1 mM to 160 mM (r = 0.995) and 0.8 μM at a signal-to-noise ratio of 3, respectively.

The efficiency of many energy storage technologies is limited by the sluggish kinetics of the oxygen evolution reaction (OER) and it is thus of great importance to develop highly active OER electrocatalysts made from earth-abundant elements. In this communication, we report a novel metal-free oxygen evolution electrode with high catalytic activity and stability through simple acidic oxidation of commercially available carbon cloth (CC). The resulting acidically oxidized CC exhibits an overpotential of 328 mV and a Tafel slope of 82 mV dec(-1) with 100% Faradaic efficiency. This electrode needs an overpotential of 477 mV to afford a current density of 10 mA cm(-2) and maintains its catalytic activity for at least 24,000 s. It offers us a low-cost flexible electrocatalytic electrode for device integration toward water splitting and rechargeable metal-air battery applications.

Wastewater irrigation for vegetable cultivation is greatly concerned about the presence of toxic metals in irrigated soil and vegetables which causes possible threats to human health. This study aimed to ascertain the accumulation of heavy metals (HMs) in edible parts of vegetables irrigated with different stages of textile dyeing wastewater (TDW). Bio-concentration factor (BCF), Estimated daily intake (EDI), and target hazard quotient (THQ) were computed to estimate human health risks and speculate the hazard index (HI) of adults and children with the consumption of HMs contaminated vegetables at recommended doses. Five vegetables (red amaranth, Indian spinach, cauliflower, tomato, and radish) in a pot experiment were irrigated with groundwater (T1) and seven stages of TDW (T2∼T8) following a randomized complete block design (RCBD) with three replications. Among the TDW stages, T8, T7, T4, and T5 exhibited elevated BCF, EDI, THQ, and HI due to a rising trend in the accumulation of Pb, Cd, Cr, and Ni heavy metals in the edible portion of the red amaranth, followed by radish, Indian spinach, cauliflower, and tomato. The general patterns of heavy metal (HM) accumulation, regarded as vital nutrients for plants, were detected in the following sequence: Zn > Mn/Cu > Fe. Conversely, toxic metals were found to be Cd/Cr > Ni > Pb, regardless of the type of vegetables. Principal Component Analysis (PCA) identified T8, T7, and T4 of TDW as the primary contributors to the accumulation of heavy metals in the vegetables examined. Furthermore, the analysis of the heavy metals revealed that the BCF, THQ, and HI values for all studied metals were below 1, except for Pb. This suggests that the present consumption rates of different leafy and non-leafy vegetables, whether consumed individually or together, provide a low risk in terms of heavy metal exposure. Nevertheless, the consumption of T8, T7, and T4 irrigated vegetables, specifically Indian spinach alone or in combination with red amaranth and radish, by both adults and children, at the recommended rate, was found to pose potential health risks. On the other hand, T2, T3, and T6 irrigated vegetables were deemed safe for consumption. These findings indicated that the practice of irrigating the vegetables with T8, T7, and T4 stages of TDW has resulted in a significant buildup of heavy metals in the soils and edible parts of vegetables which are posing health risks to adults and children. Hence, it is imperative to discharge the T8, T7, and T4 stages of TDW after ETP to prevent the contamination of vegetables and mitigate potential health risks.

An Fe-doped CoP nanoarray behaves as a robust 3D monolithic multifunctional catalyst for electrolytic and hydrolytic hydrogen evolution with high activity. Its two-electrode electrolyzer needs a cell voltage of only 1.60 V for 10 mA cm^-2 water-splitting current. It also catalyzes effectively NaBH₄ hydrolysis with a low activation energy of ≈39.6 kJ mol^-1 and a hydrogen generation rate of 6.06 L min^-1 g^-1 .

High-performance supercapacitors require the design and development of electrode materials with high conductivity and a large electrolyte-accessible surface area. Here, the use of a conductive NiCoP nanoarray on nickel foam (NiCoP/NF) as a superior pseudocapacitor electrode is demonstrated. This 3D electrode exhibits high areal capacitances of 9.2 and 5.97 F cm^-2 at current densities of 2 and 50 mA cm^-2 , respectively, with good rate capability and cycling stability. The asymmetric supercapacitor (ASC) device assembled using NiCoP/NF as positive electrode and active carbon as negative electrode delivers a high energy density of 1.16 mWh cm^-2 at a power density of 1.6 mW cm^-2 with 72 % retention of its initial specific capacitance after 2000 cycles at 50 mA cm^-2 . The practical use is further demonstrated with two such ASC devices in series to light six LED indicators and also to drive an alkaline water electro- lyzer using NiCoP/NF as both cathode and anode for hydrogen production.