Ti2N nitride MXene evokes the Mars-van Krevelen mechanism to achieve high selectivity for nitrogen reduction reaction

We address the low selectivity problem faced by the electrochemical nitrogen (N2) reduction reaction (NRR) to ammonia (NH3) by exploiting the Mars-van Krevelen (MvK) mechanism on two-dimensional (2D) Ti2N nitride MXene. NRR technology is a viable alternative to reducing the energy and greenhouse gas emission footprint from NH3 production. Most NRR catalysts operate by using an associative or dissociative mechanism, during which the NRR competes with the hydrogen evolution reaction (HER), resulting in low selectivity. The MvK mechanism reduces this competition by eliminating the adsorption and dissociation processes at the sites for NH3 synthesis. We show that the new class of 2D materials, nitride MXenes, evoke the MvK mechanism to achieve the highest Faradaic efficiency (FE) towards NH3 reported for any pristine transition metal-based catalyst—19.85% with a yield of 11.33 μg/cm2/hr at an applied potential of − 250 mV versus RHE. These results can be expanded to a broad class of systems evoking the MvK mechanism and constitute the foundation of NRR technology based on MXenes.

The Carbon Footprint of a Public Sector University Before and During the COVID-19 Lockdown.

<p>Carbon footprint (CF) is a measure of greenhouse gas emissions generated from daily human-induced activities as carbon dioxide equivalent. This study is an attempt to represent a consumption-based CF study from the scope of transportation, electricity, and waste generation for University of the Punjab (PU), Lahore under the WRI/WBCSD greenhouse gas protocol corporate standards. Data acquired through fieldwork, questionnaire surveys, direct sampling, and existing records for the year 2019-20 suggested that electricity is the greatest contributor of CO2 emissions at 59%, followed by transportation at 36%, and waste generation at approximately 5%. The total CF(CO2_eq) generated from different sources is about 18360.62MT for one year. The recent COVID-19 lockdown has offered inimitable prospect to compare the carbon footprint of one of the largest higher education institutes of Pakistan before and during this pandemic. The data can serve for tracking, assessing, and setting goals for greenhouse gas emission reduction programs in future.</p>

Climate Change in the Attention Arena of the Middle Class

Good intentions by the middle class are not always well guided and do not always lead to measurable or significant results. For example, efforts to limit greenhouse gas emissions may hold broad appeal but can still have negligible impact. Therefore, it is suggested to embark on “Apollo projects”, which bundle the potential and willingness of the middle class. These projects should focus on the development of specific technologies, with economic advantages to support their spread throughout the world. Doing so will harness the middle class in support of greenhouse gas emission reductions in the gigaton-range. Such pan-national projects, for example, could address emission-free ship- or air-propulsion, the electrification of heating or of processes in the chemical industry.

Study on the Mercury Migration in Clinker-Producing

Mercury is one most important global pollutants in the environment. The article studied the mercury migration according to the mercury migration in the cement process, in which a model for the relationship between the mercury input, internal circulation and output is built. In the model, mercury concentration in each stage of the process was calculated and characterized with different input, which were Consistent with actual verification, and then the reasonable method was advised to prevent the mercury pollution. The simulation showed that the mercury input is below 0.1g/t.cli, and the mercury gas emission concentration is below 0.05 mg/Nm3 whenever the mode of raw mill is on or off. But once the mercury input is over 0.23 g/t.cli, the mercury gas emission concentration is over 0.05mg/Nm3 although the mode of raw mill is on. The mercury content in ERM and KA is almost ten times higher than raw material, and the mercury content in KA is almost ten times higher than raw meal extraction, and multiples increase with higher mercury input as well. Even if mercury is continuously enriched internal, there is no limit of mercury concentration saturation.