MXene-containing composite electrodes for hydrogen evolution: material design aspects and approaches for electrode fabrication

This work explores the possibilities for the processing of Ni- and Ti3C2Tx (T = OH, O) MXene-containing composite electrodes, by co-pressing and plastic deformation or by etching of the electrodes prepared directly by self-propagation high-temperature synthesis (SHS). Various material design approaches were also explored. In order to tune the Ti3C2 interlayer distance in Ti3C2Al MAX phase, an introduction of additional Al to form Ti3C2Alz materials with z > 1 was attempted. Self-propagation high-temperature synthesis of powder mixtures with extra Ni and Al content (e.g. Ni:Ti:Al:C = 1:2:3:1) resulted in SHS products containing Ti3C2Alz z > 1 material and Ni–Al alloys. Further etching of these products in 10M NaOH allowed the direct formation of electrodes with active surface containing Ti3C2Tx (T = OH, O) MXene- and Raney nickel-containing composites. The electrochemical studies were focused on hydrogen evolution and showed the potential for boosting the electrochemical reaction in Ni and MXene-containing composite electrodes, especially at high current densities. The guidelines for the processing of such electrodes under fluorine-free conditions are proposed and discussed.publishe

Measurement of Natural Occurring Radio nuclides (NORMs) in Soil using Gamma- ray Spectrometry

The aim of this work is focused on preparation and using gamma- ray spectrometry to investigate and demonstrate a method to determine and evaluate natural radio nuclides which are uranium, thorium and potassium and their activity concentrations, radium equivalent activity , absorbed dose rates in air at one meter above the ground surface and the annual external and internal effective dose rates . The spectrometer consists of NaI (Tl ) detector coupled with preamplifier and ADC of 4096 Chanel memory , CASSY type. The suitable gain was determined. The efficiency , energy calibration and resolution had been measured by using some standard source .. In order to evaluate the radiological impact for the population , four soil samples have been Collected from different localities in middle area of Najaf province , and measured in which 238U ,232Th and 40K were noted. The value of activity concentration ranged from 4.84±0.52 to 17.52±0.94, 5.92±0.31 to 7.07±0.344 and 103.39±2.52 to 185.48±2.09 (Bq kg-1) for 238U, 232Th and 40K respectively . The calculated values of radium equivalent activity (Raeq ) ranged from 25.25 to 33.94 (Bq kg-1) whereas absorbed doses varied from 12.35 to 16.09 (Bq kg-1) . Annual effective Doses were found to be in the range (0.061) to (0.079) and (0.015) to (0.020) (mSv) for indoor and Outdoor respectively . The comparison between our results and standard levels recommended by the IAEA and UNSCEAR show low radiation level