Electrochemical nitrate reduction over bimetallic Pd-Sn nanocatalysts with tunable selectivity toward benign nitrogen.

Nitrate is recognized as a highly impactful water contaminant among various pollutants in water. To address the ever-growing demand for water purification, this work investigates the bimetallic palladium (Pd) and tin (Sn) catalysts, which are electrochemically deposited on stainless steel mesh support (Pd-Sn/SS) for the selective conversion of harmful nitrate (NO3-) into benign nitrogen (N2) gas. Results indicate that the bimetallic composition in Pd-Sn/SS electrodes substantially influenced the reaction route for nitrate reduction as well as the performance of nitrate transformation and nitrogen selectivity. It is found that the electrode prepared from Pd:Sn = 1:1 (mole ratio) demonstrates an outstanding nitrate conversion of 95%, nitrogen selectivity of 88%, and nitrogen yield of 82%, which outperform many reported values in the literature. The electrochemically synthesized bimetallic electrode proposed herein enables a new insight for promoting the reactivity and selectivity of nitrate reduction in water.

Visible light-driven photocatalytic bacterial inactivation on PPE, supported by the DFT and bactericidal study.

A novel ZnO-MoO3-ZnMoO3@graphene GZM composite catalyst prepared by microwave hydrothermal process for personal protective equipment textiles (PPE) is presented in this study. The results indicated that the GZM with defect vacancy sites of two types as observed by EPR showed significantly superior inactivation of the E. coli bacteria compared to GZM without the lower defect vacancy sites and concomitant lower electron densities. Photocatalytic activated oxidation by the GZM composites coatings was observed to proceed in acceptable times as well as the bacterial inactivation (log bact. C/Co > 107 within 3 h). Defect sites in the GZM seem to be important leading to the bacterial inactivation process. DFT calculations on the GZM with and without catalyst defect sites were carried out. The electron densities were estimated by the Fourier mapping. The results found in this study showed the potential of GZM-PPE for practical applications.

Enhanced nitrate reduction over functionalized Pd/Cu electrode with tunable conversion to nitrogen and sodium hydroxide recovery.

Development of heteroatomic electrocatalysts with a particular geometric structure for wastewater denitrification remains a formidable challenge. Herein, we reported the fabrication of a series of PdCu electrodes with Pd electrodeposition times varying from 60 s to 360 s. Physiochemical and electrochemical techniques were used to analyze the structure, morphology and activity of as prepared catalytic electrodes. XRD data revealed the formation of a PdCu alloy, while a reduced particle sizes (ca. 5.3 nm) and a uniform distribution of Pd over Cu was demonstrated by TEM. The XPS measurement indicated the presence of redox (Pd0 and Cu+2) states hence demonstrating the formation of a PdCu alloy. A nitrate removal efficiency of ~98 %, N2 selectivity ~86 % with an alkali recovery of 335 mM was obtained over Pd/Cu 180 s at 0.68 mA cm-2. Enhanced nitrate reducibility and extended durability reveal the viability of a novel electrocatalytic and electrodialysis system for degrading NO3- in water, as well as a system for efficiently recovering liquid alkali.

A review on advances in green treatment of glycerol waste with a focus on electro-oxidation pathway.

Over the past decades, research efforts are being devoted into utilizing the biomass waste as a major source of green energy to maintain the economic, environmental, and social sustainability. Specifically, there is an emerging consensus on the significance of glycerol (an underutilised waste from biodiesel industry) as a cheap, non-toxic, and renewable source for valuable chemicals synthesis. There are numerous methods enacted to convert this glycerol waste to tartronic acid, mesoxalic acid, glyceraldehyde, dihydroxyacetone, oxalic acid and so on. Among these, the green electro-oxidation technique is one of the techniques that possesses potential for industrial application due to advantages such as non-toxicity process, fast response, and lower energy consumption. The current review covers the general understanding on commonly used techniques for alcohol (C1 & C2) conversion, with a specific insight on glycerol (C3) electro-oxidation (GOR). Since catalysts are the backbone of chemical reaction, they are responsible for the overall economy prospect of any processes. To this end, a comprehensive review on catalysts, which include noble metals, non-noble metals, and non-metals anchored over various supports are incorporated in this review. Moreover, a fundamental insight into the development of future electrocatalysts for glycerol oxidation along with products analysis is also presented.

Glycerol Waste Valorization to Mesoxalic Acid Over a Bimetallic Pt-Pd/CNT Catalyst in Alkaline Medium.

Glycerol electro-oxidation offers a green route to produce the high value added chemicals. Here in, we report the glycerol electro-oxidation over a series of multi walled carbon nano tubes supported monometallic (Pt/CNT and Pd/CNT) and bimetallic (Pt-Pd/CNT) catalysts in alkaline medium. The cyclic voltammetry, linear sweep voltammetry and chronoamperometry measurements were used to evaluate the activity and stability of the catalysts. The Pt-Pd/CNT electrocatalyst exhibited the highest activity in terms of higher current density (129.25 A/m²) and electrochemical surface area (382 m²/g). The glycerol electro-oxidation products formed at a potential of 0.013 V were analyzed systematically by high performance liquid chromatography. Overall, six compounds were found including mesoxalic acid, 1,3-dihydroxyacetone, glyceraldehyde, glyceric acid, tartronic acid and oxalic acid. A highest mesoxalic acid selectivity of 86.42% was obtained for Pt-Pd/CNT catalyst while a maximum tartronic acid selectivity of 50.17% and 46.02% was achieved for Pd/CNT and Pt/CNT respectively. It was found that the introduction of Pd into Pt/CNT lattice facilitated the formation of C3 products in terms of maximum selectivity achieved (86.42%) while the monometallic catalysts (Pd/CNT and Pt/CNT) showed a poor performance in comparison to their counterpart.