Mohamed Rabia

A High-Sensitivity Potentiometric Mercuric Ion Sensor Based on m-Toluidine Films

A sensor of m-toluidine polymer film coated platinum electrode was fabricated by the electropolymerization using cyclic voltammetry technique for the detection of mercury ions (Hg²⁺) in aqueous solution. This paper was carried out using the simple potentiometric method and confirmed by a cyclic voltammetry technique. The effects of the polymer film thickness and pH of Hg²⁺ solutions on the response of the sensor were studied. Moreover, the stability, sensitivity, and selectivity of the m-toluidine sensor were investigated. The optimum thickness of the polymer film was obtained after ten cyclic voltammetric runs. This film has a Nernstian response slope of 29.19 mV/decade with a detection limit of 3.54 × 10^-5 M at 293 K by the simple potentiometric method. In addition, it has a sensitivity of 4 × 10^-7 AM^-1 with a detection limit of 1.33 × 10^-7 M by the cyclic voltammetry method. Moreover, the sensor is specific to Hg²⁺ ions in the presence of other ions, such as Na⁺, K⁺, Mg²⁺, Ca²⁺, Co²⁺, Ni²⁺, Zn²⁺, and Pb²⁺. Furthermore, the most stable response of the sensor to Hg²⁺ ions in the solution of pH ranged from 4 to 6.4 for a lifetime of about eleven weeks. Moreover, the sensor was applied for detection of four natural samples: tap water; underground water; first distillate water; and another sample wasted with Hg²⁺ ions.

Photocatalytic properties of PbS/graphene oxide/polyaniline electrode for hydrogen generation

In this work, roll-graphene oxide (Ro-GO), polyaniline (PANI) nano/microparticles, and PbS nanoparticles were prepared by modified Hammer, oxidative polymerization, and chemical bath deposition methods, respectively. These nano/microstructures were characterized, optimized, and designed to form PbS/Ro-GO/PANI nano/microcomposite. Also, the ratios of PbS and Ro-GO were optimized, and the optimized composition of the used composite was 0.4 g PANI, 0.125 g Ro-GO, and 0.075 g PbS. The band gap values for PANI, PbS, Ro-GO, and PbS/Ro-GO/PANI rocomposite were 3, 1.13, 2.86, (1.16, 2) eV, respectively. Two photoelectrode assemblies, Au/PbS/Ro-GO/PANI and PbS/Ro-GO/PANI/ITO/glass were used for the photoelectrochemical (PEC) hydrogen generation. In the first assembly 45 nm- Au layer was sputtered on the surface of a disk of PbS/Ro-GO/PANI composite. For the second assembly, a disk of PbS/Ro-GO/PANI composite was glued on ITO glass using Ag-THF paste. The lifetime efficiency values were 64.2 and 43.4% for the first and second electrode for 2 h, respectively. Finally, the incident photon-to-current conversion efficiency (IPCE) and photon-to-current efficiency (ABPE) were calculated under monochromatic illumination conditions. The optimum IPCE efficiency at 390 nm was 9.4% and 16.17%, whereas ABPE % efficiency was 1.01% and 1.75% for Au/PbS/Ro-GO/PANI and PbS/Ro-GO/PANI/ITO/glass, respectively.

Preparation of polyaniline/PbS core-shell nano/microcomposite and its application for photocatalytic H 2 electrogeneration from H 2 O

Lead sulfide (PbS) and polyaniline (PANI) nano/microparticles were prepared. Then, PANI/PbS core-shell nano/microcomposites (I, II, and III) were prepared by oxidative polymerization of different aniline concentrations (0.01, 0.03, and 0.05 M), respectively, in the presence of 0.05 M PbS. FT-IR, XRD, SEM, HR-TEM, and UV-Vis analyses were carried out to characterize the samples. From the FT-IR data, there are redshifts in PbS and PANI nano/microparticles bands in comparison with PANI/PbS nano/microcomposites. The average crystallite sizes of PANI/PbS core-shell nano/microcomposites (I, II, and III) from XRD analyses were 46.5, 55, and 42.16 nm, respectively. From the optical analyses, nano/microcomposite (II) has the optimum optical properties with two band gaps values of 1.41 and 2.79 eV. Then, the nano/microcomposite (II) membrane electrode supported on ITO glass was prepared and applied on the photoelectrochemical (PEC) H2 generation from H2O. The characteristics current-voltage and current-time behaviors were measured at different wavelengths from 390 to 636 nm. Also, the incident photon-to-current conversion efficiency (IPCE) under monochromatic illumination condition was calculated. The optimum values for IPCE were 36.5 and 35.2% at 390 and 405 nm, respectively. Finally, a simple mechanism for PEC H2 generation from H2O using the nano/microcomposite (II) membrane electrode was mentioned.