In situ growth of copper oxide on MXene by combustion method for electrochemical ammonia production from nitrate.

The elimination of the nitrogen pollutant nitrate ions through the electrochemical synthesis of ammonia is an important and environment friendly strategy. Electrochemical nitrate reduction requires highly efficient, selective, and stable catalysts to convert nitrate to ammonia. In this work, a composite of copper oxide and MXene was synthesized using a combustion technique. As reported, nitrate ions are effectively adsorbed by CuxO (CuO & Cu2O) nanoparticles. Herein, MXene is an excellent assembly for anchoring CuxO on its layered surface because it has a strong support structure. Powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analyses show the presence of oxidation states of metal ions and the formation of CuxO nanofoam anchors on the surface of MXene (Ti3C2Tx). The optimized CuxO/Ti3C2Tx composite exhibits an improved nitrate reduction reaction. The electrochemical studies of CuxO/Ti3C2Tx show an interesting nitrate reduction reaction (NO3RR) with a current density of 162 mA cm-2. Further, CuxO/Ti3C2Tx shows an electrocatalytic activity with an ammonia production of 41 982 µg h-1 mcat-1 and its faradaic efficiency is 48% at -0.7 V vs. RHE. Thus, such performance by CuxO/Ti3C2Tx indicates a well-suitable candidate for nitrate ion conversion to ammonia.

Functional Alkali Metal-Based Ternary Chalcogenides: Design, Properties, and Opportunities.

The search for novel materials has recently brought research attention to alkali metal-based chalcogenides (ABZ) as a new class of semiconducting inorganic materials. Various theoretical and computational studies have highlighted many compositions of this class as ideal functional materials for application in energy conversion and storage devices. This Perspective discusses the expansive compositional landscape of ABZ compositions that inherently gives a wide spectrum of properties with great potential for application. In the present paper, we examine the technique of synthesizing this particular class of materials and explore their potential for compositional engineering in order to manipulate key functional properties. This study presents the notable findings that have been documented thus far in addition to outlining the potential avenues for implementation and the associated challenges they present. By fulfilling the sustainability requirements of being relativity earth-abundant, environmentally benign, and biocompatible, we anticipate a promising future for alkali metal chalcogenides. Through this Perspective, we aim to inspire continued research on this emerging class of materials, thereby enabling forthcoming breakthroughs in the realms of photovoltaics, thermoelectrics, and energy storage.

Decoration of boron nanoparticles on a graphene sheet for ammonia production from nitrate.

Clean water and sanitation are two of the most important challenges worldwide and the main source for freshwater is groundwater. Nowadays, water is polluted by human activities. Concern about the presence of nitrates (NO3-) in groundwater is increasing day-by-day due to the intensive use of fertilizers and other anthropogenic sources, such as sewage or industrial wastewater discharge. Thus, the main solution available is to remove NO3- from groundwater and transfer it back to a usable nitrogen source. Electrochemical reduction of NO3- to ammonia (NH3) under ambient conditions is a highly desirable method and it needs an efficient electrocatalyst. In this work, we synthesized a composite of amorphous boron with graphene oxide (B@GO) as an efficient catalyst for the nitrate reduction reaction. XRD and TEM analysis revealed an amorphous boron decoration on the graphene oxide sheet, and XPS confirmed that no bonding between boron and carbon occurs. In B@GO, a stronger defect carbon peak was observed than in GO and there was a random distribution of boron particles on the surface of the graphene nanosheets. Amorphous boron exhibits a higher bond energy, more reactivity, and chemical activity toward nitrate ions, which could be due to the lone pair present in the B atoms and could also be due to the edge oxidized B atoms. B@GO has a high number of active sites exposed leading to excellent nitrate reduction performance with a faradaic efficiency of 61.88% and good ammonia formation rate of 40006 µg h-1 mcat-1 at -0.8 V versus reversible hydrogen electrode.

Exploring the Role of Short Chain Acids as Surface Ligands in Photoinduced Charge Transfer Dynamics from CsPbBr3 Perovskite Nanocrystals.

The most commonly used surface capping ligands, like oleic acid and oleylamine, passivate the surface of perovskite nanocrystals (PNCs) to enhance their stability and optical properties. However, due to their inherent insulating nature, charge transport across the surface of the PNCs is hindered, limiting their application in devices. In this study, we have post-treatment CsPbBr3 PNCs with short chain ligands benzoic acid (BA) and ascorbic acid (AA) and observed that both acid-treated PNCs show enhanced stability and optical properties. Still, BA-treated PNCs show the highest charge transport rate due to their conjugating nature. The photoelectrochemical measurements also show the most efficient electron flow across the surface of the PNC with BA-treated PNCs. A longer carrier lifetime and fast charge transfer make BA-treated PNCs ideal candidates for application in real-life devices.

Amine-Free Synthetic Route: An Emerging Approach to Making High-Quality Perovskite Nanocrystals for Futuristic Applications.

In recent years, colloidal cesium lead halide (CsPbX3) perovskite nanocrystals (PNCs) have attracted significant attention from researchers due to their unique optical properties and potential use in optoelectronic applications. In colloidal synthesis, oleic acid and oleylamine are commonly used as surface-capping ligands. Although oleylamine plays a crucial role in maintaining the colloidal stability and surface passivation of PNCs, its dynamic equilibrium with oleic acid leads to the formation of labile oleylammonium, which pulls halides from the surface of PNCs and thus degrades the crystals. In this Perspective, we summarize the various approaches for eliminating the amines to make high-quality, photostable, and amine-free CsPbX3 PNCs. In addition, we look over the prospects of these PNCs regarding stability in different environmental conditions, photoluminescence properties, and optoelectronic device performance. This perspective will give a broad overview of amine-free PNCs starting from their synthesis, challenges, and optoelectronic properties to their future prospects.