Three-dimensional mesoporous hierarchical carbon nanotubes/nickel foam-supported gold nanoparticles as a free-standing sensor for sensitive hydrazine detection

Unveiling carcinogenic pollutant levels in environmental water samples through facile fabrication of gold nanoparticles on sulfur-doped graphitic carbon nitride

Extensive utilization of pesticides and herbicides to boost agricultural production increased the environmental health risks, which can be mitigate with the aid of highly sensitive detection systems. In this study, an electrochemical sensor for monitoring the carcinogenic pesticides in the environmental samples has been developed based on sulfur-doped graphitic-carbon nitride-gold nanoparticles (SCN-AuNPs) nanohybrid. Thermal polycondensation of melamine with thiourea followed by solvent exfoliation via ultrasonication leads to SCN formation and electroless deposition of AuNPs on SCN leads to SCN-AuNPs nanohybrid synthesis. The chemical composition, S-doping, and the morphology of the nanohybrid were confirmed by various microscopic and spectroscopic tools. The as-synthesized nanohybrid was fabricated with glassy carbon (GC) electrode for determining the carcinogenic hydrazine (HZ) and atrazine (ATZ) in field water samples. The present sensor exhibited superior electrocatalytic activity than GC/SCN and GC/AuNPs electrodes due to the synergism between SCN and AuNPs and the amperometric studies showed the good linear range of detection of 20 nM-0.5 mM and 500 nM-0.5 mM with the limit of detection of 0.22 and 69 nM (S/N = 3) and excellent sensitivity of 1173.5 and 13.96 μA mM-1 cm-2 towards HZ and ATZ, respectively. Ultimately, the present sensor is exploited in environmental samples for monitoring HZ and ATZ and the obtained results are validated with high-performance liquid chromatography (HPLC) technique. The excellent recovery percentage and close agreement with the results of HPLC analysis proved the practicability of the present sensor. In addition, the as-prepared materials were utilized for the photocatalytic degradation of ATZ and the SCN-AuNPs nanohybrid exhibited higher photocatalytic activity with the removal efficiency of 93.6% at 90 min. Finally, the degradation mechanism was investigated and discussed.

Biomass Derived Biofluorescent Carbon Dots for Energy Applications: Current Progress and Prospects

Biomass resources are often disposed of inefficiently and it causes environmental degradation. These wastes can be turned into bio-products using effective conversion techniques. The synthesis of high-value bio-products from biomass adheres to the principles of a sustainable circular economy in a variety of industries, including agriculture. Recently, fluorescent carbon dots (C-dots) derived from biowastes have emerged as a breakthrough in the field, showcasing outstanding fluorescence properties and biocompatibility. The C-dots exhibit unique quantum confinement properties due to their small size, contributing to their exceptional fluorescence. The significance of their fluorescent properties lies in their versatile applications, particularly in bio-imaging and energy devices. Their rapid and straight-forward production using green/chemical precursors has further accelerated their adoption in diverse applications. The use of green precursors for C-dot not only addresses the biomass disposal issue through a scientific approach, but also establishes a path for a circular economy. This approach not only minimizes biowaste, which also harnesses the potential of fluorescent C-dots to contribute to sustainable practices in agriculture. This review explores recent developments and challenges in synthesizing high-quality C-dots from agro-residues, shedding light on their crucial role in advancing technologies for a cleaner and more sustainable future.

Controllable preparation of long wavelength carbon dots and their application in fluorescence detection

By adjusting the reactants and reaction conditions, the particle size and surface state of fluorescent carbon dots (CDs) can be controlled, and CDs with different photoluminescence colors can be finally prepared. However, this multi-step procedure is relatively time-consuming and complex. Therefore, it is of great significance to explore a more convenient and efficient preparation route. In this paper, SA (P-aminobenzenesulfonic acid) and οPD (o-phenylenediamine) were used as precursors, and water and ethanol were used as reaction solvents. By adjusting the proportion of the precursor or reaction solvent, self-doping and co-doping of the precursor were realized, and CDs with various fluorescent colors were finally prepared. It was found that red-emission CDs (r-CDs) could be prepared with SA and οPD as precursors and water as the solvent. Through comparative study, it was found that r-CDs were affected by H+ in the formation process and photoluminescence process. The fluorescence stability of r-CDs indicated that they have good selectivity for some metal ions. The r-CDs prepared in this paper realized the specific recognition of Cu2+ and Ag+ through the "off-on" process, and the detection limits were 0.165 μm and 1.53 μm, respectively. And this test has the potential for practical qualitative testing.

A redox-active covalent organic framework for the efficient detection and removal of hydrazine

The removal and detection of soluble hydrazine is of importance due to its harm to soil and subterranean water, but challenging. Herein, we preferentially disposed a porous and redox active covalent-organic framework (DAAQ-TFP COF, denoted as DQ-COF) to simultaneously removal and detect hydrazine. Electroactive sites (anthraquinone units) can be intelligently incorporated into the channel walls/pores of COF. DQ-COF has high crystallinity and good thermal stability, and DQ-COF dropped onto nickel matrix (DQ-COF/Ni composite) still retains high surface area, characterized by PXRD, FT-IR, nitrogen adsorption and TGA. Subsequently, a detailed study of DQ-COF towards hydrazine uptake and detection potentials is explored. DQ-COF as adsorbent unfolds strong removal ability towards hydrazine, the maximum removal capacity of which is up to 1108 mg g^-1, following Friedrich and pseudo-second-order kinetic models. Meanwhile, the DQ-COF supported on nickel renders attractive electrochemical properties, which is efficiently responsive to hydrazine at a part per billion (ppb) level, coupled with a wide linear range (0.5 ˜ 1223 μM), low detection limit (0.07 μM) and high anti-interference ability. There is no other COFs with such a favorable capability in synchronous removal and selective detection towards hydrazine, probably applying in superintending water quality and disposing wastewater.

A dual-excitation fluorescent probe EuIII-dtpa-bis(HBT) for hydrazine detection in aqueous solutions and living cells

The Eu^III-dtpa-bis(HBT) dual-excitation fluorescence probe has good selectivity and strong anti-interference ability for the detection of N₂H₄.