Publications

In this Letter, we describe the development of a CoSe2 nanowires array on carbon cloth (CoSe2 NW/CC) through a facile two-step hydrothermal preparative strategy. As a novel 3D nanoarray electrode for electrochemical hydrogen evolution, CoSe2 NW/CC exhibits excellent catalytic activity and durability in acidic media. It needs overpotentials of 130 and 164 mV to approach 10 and 100 mA cm(-2), respectively, and its activity is maintained for at least 48 h. This work would open up new avenues for the rational design of a variety of arrayed transition-metal chalcogenide cathodes for technological application toward large-scale hydrogen generation from water.

Abstract NH 3 is one of the largest‐volume industrial chemicals synthesized in the world. It not only is a kind of important chemical base materials to produce fertilizers, plastics and explosives, but also can serve as a clean energy carrier with high hydrogen content for a sustainable energy supply. N 2 is the most abundant gas in atmosphere, but its inert character caused by the strong triple bond, impedes itself from being converted to NH 3 . In nature, this shortcoming is overcome by biological N 2 fixation utilizing nitrogenase enzymes. Industrially, fixation of N 2 ‐to‐NH 3 prevailingly depends on Haber‐Bosch process using Ru‐ or Fe‐based catalysts, but this process consumes large energy and emits heavy carbon which increases crisis of global warming.

An electrochemical nitrite sensor probe is introduced herein using a modified flat glassy carbon electrode (GCE) and SrTiO₃ material doped with spherical-shaped gold nanoparticles (Au-NPs) and polypyrrole carbon (PPyC) at a pH of 7.0 in a phosphate buffer solution. The nanocomposites (NCs) containing Au-NPs, PPyC, and SrTiO₃ were synthesized by ultrasonication, and their properties were thoroughly characterized through structural, elemental, optical, and morphological analyses with various conventional spectroscopic methods, such as field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller method. The peak currents due to nitrite oxidation were characterized in detail and analyzed using conventional cyclic voltammetry (CV) as well as differential pulse voltammetry (DPV) under ambient conditions. The sensor response increased significantly from 0.15 to 1.5 mM of nitrite ions, and the sensor was fabricated by coating a conducting agent (PEDOT:PSS) on the GCE to obtain the Au-NPs/PPyC/SrTiO₃ NCs/PEDOT:PSS/GCE probe. The sensor's sensitivity was determined as 0.5 μA/μM∙cm² from the ratio of the slope of the linear detection range by considering the active surface area (0.0316 cm²) of the flat GCE. In addition, the limit of detection was determined as 20.00 ± 1.00 µM, which was found to be satisfactory. The sensor's stability, pH optimization, and reliability were also evaluated in these analyses. Overall, the sensor results were found to be satisfactory. Real environmental samples were then analyzed to evaluate the sensor's reliability through DPV, and the results showed that the proposed novel electrochemical sensor holds great promise for mitigating water contamination in the real samples with the lab-made Au-NPs/PPyC/SrTiO₃ NC. Thus, this study provides valuable insights for improving sensors for broad environmental monitoring applications using the electrochemical approach.

The present communication reports on a rapid exfoliation method for high-yield production of few-layer graphene flakes on a large scale from graphite within seconds with the use of chlorosulfonic acid and H2O2 as exfoliating agents.

Electrochemical N2 reduction reaction (NRR) is an environmentally benign and sustainable approach for NH3 synthesis under ambient conditions, which needs efficient electrocatalyst to meet the enormous challenge of activating the inert N2 molecule. Recently, TiO2 emerges as an active NRR electrocatalyst with advantages of abundance, nontoxicity, and high thermal stability. Heteroatom doping is an effective oxygen vacancy introduction strategy to manufacture unique electron and structure properties of metal oxides, which will greatly influence the catalysts’ activity. In this work, we developed Mn-doped TiO2 nanospheres (Mn-TiO2) for electrochemical NRR. In 0.1 M Na2SO4, Mn-TiO2 shows a large NH3 yield rate of 20.05 μg h–1 mgcat.–1 and a high Faradaic efficiency of 11.93%, which are much higher than undoped TiO2. The mechanism of performance improvement is uncovered by density functional theory calculations.

Every day, the risk of water pollution grows. According to the World Health Organization (WHO), approximately half of the population of poor countries suffers from health problems linked to chemically or microbially contaminating drinkable water. Here in the present study, powder of taro-rhizome was used for preparation of supported bimetallic catalyst (Ag-Cu/TP). Characterization techniques used for analysis were XRD, TEM, SEM, FTIR and EDS. The prepared catalyst was then used in the catalytic reduction of chemical pollutants, including 4-nitrophenol (4-NP), 2,4,6-trinitrophenol (TNP), 2-nitrophenol (2-NP), methyl orange (MO), Acid Red 27 or amaranth (AM), Congo red (CR), Rhodamine B (RhB) and methyl red (MR). Turnover frequency was calculated for nitrophenol reductions, which were 0.98 min−1 for 2-NP and 3.45 min−1 for 4-NP. The Ag-Cu/TP catalyst shows outstanding performance and 99.4% of 4-NP was reduced just in 5 min with pseudo-first order constant of 5.24 × 10−3s−1, while 97% reduction of 2-NP took 17 min with the pseudo-first order constant of 1.01 × 10−3s−1. The prepared Ag-Cu/TP catalyst was packed into a glass column and organic dyes containing water were filtered through it to test the cleaning effectiveness of water from dyes. Excellent dye reduction was achieved. The prepared column reactor works excellent in the remediation of dyes and reduces about 68.7% CR. In addition, stability and reusability study showed exceptional reusability up to 5 times with very small loss of activity and was stable for up to 10 days.

A Cu(OH)₂ @CoCO₃ (OH)₂ ·nH₂ O (CCHH) core-shell heterostructure nanowire array acts as robust 3D oxygen evolution reaction catalyst. It needs an overpotential of 270 mV to drive 50 mA cm^-2 in 1.0 m KOH, outperforming CCHH nanowire arrays on copper foam and most reported Co-based oxygen evolution reaction catalysts in alkaline media. It is also efficient for methanol electrooxidation.