RSC Advances

Pansare, Amol V.; Shedge, Amol A.; Sonawale, Maryappa C.; Pansare, Shubham V.; Mahakal, Akshay D.; Khairkar, Shyam R.; Chhatre, Shraddha Y.; Kulal, Dnyaneshwar K.; Patil, Vishwanath R.

doi: 10.1039/d1ra07195epmid: 35425164

In this study, we focus on the biomimetic development of small molecules and their biological sensing with DNA. The binding of herring sperm deoxyribonucleic acid (hs-DNA) with naturally occurring bioactive small molecule α-amyrin acetate (α-AA), a biomimetic – isolated from the leaves of Ficus (F.) arnottiana is investigated. Collective information from various imaging, spectroscopic and biophysical experiments provides evidence that α-AA is a minor groove sensor of hs-DNA and preferentially binds to the A–T-rich regions. Interactions of different concentrations of small molecule α-AA with hsDNA were evaluated via various analytical techniques such as UV-Vis, circular dichroism (CD) and fluorescence emission spectroscopy. Fluorescence emission spectroscopy results suggest that α-AA decreases the emission level of hsDNA. DNA minor groove sensor Hoechst 33258 and intercalative sensor EB, melting transition analysis (TM) and viscosity analysis clarified that α-AA binds to hs-DNA via a groove site. Biophysical chemistry and molecular docking studies show that hydrophobic interactions play a major role in this binding. The present research deals with a natural product biosynthesis-linked chemical–biology interface sensor as a biological probe for α-AA: hs-DNA.

Qi, Ping; Gao, Xiaoxu; Wang, Jian; Liu, Huimin; He, Dehua; Zhang, Qijian

doi: 10.1039/d1ra08002dpmid: 35425192

Ammonia (NH3) is an important feedstock in chemical industry. Nowadays NH3 is mainly produced via the industrialized Haber–Bosch process, which requires substantial energy input, since it operates at high temperatures (400–650 °C) and high pressures (20–40 Mpa). From the energy conservation point of view, it is of great significance to explore an alternative avenue to synthesize NH3, which is in line with the concept of sustainable development. Very recently, photocatalytic N2 fixation (PNF) has been discovered as a safe and green approach to synthesize NH3, as it utilizes the inexhaustible solar energy and the abundant N2 in nature to synthesize NH3 under mild conditions. A highly efficient catalyst is the core of PNF. Up to now, extensive studies have been conducted to design efficient catalysts for PNF. Summarizing the catalysts reported for PNF and unraveling their reaction mechanisms could provide guidance for the design of better catalysts. In this review, we will illustrate the development of catalysts for PNF, including semiconductors, plasmonic metal-based catalysts, iron-based catalysts, ruthenium-based catalysts and several other catalysts, point out the remaining challenges and outline the future opportunities, with the aim to contribute to the development of PNF.

Liu, Zengchen; Wang, Like; Wang, Baodui; Chen, Yahong; Tian, Fengshou; Xue, Yingying; Li, Yanxia; Zhu, Wenping; Yang, Weijie

doi: 10.1039/d1ra08092jpmid: 35425208

As a class of important carbon nanomaterial, carbonized polymer dots (CPDs), also called carbon dots (CDs), have aroused wide interest owing to their unique water solubility, fluorescence properties, and rich surface functional groups. However, the directional tuning of the fluorescence properties of CPDs remains incomplete because of the influence of many factors like diameter, solvent and surface groups. Particularly, most carbonized polymer dots are synthesized in a neutral pH environment. Herein, by modulating the pH (strongly acidic or alkaline) of dextrin water solution, bicolor fluorescence emission (blue and yellow) CPDs were prepared by a hydrothermal reaction. Through systematic characterization, it was found that the different fluorescence properties are regulated by the diameters and surface groups of the carbon cores. Simultaneously, the pH value affected the nucleation process. Based on the excellent fluorescence properties, cell fluorescence imaging and cytotoxicity were tested. The bicolor fluorescence CPDs obtained by tuning the pH provide an important theoretical basis for the design of broadband CPDs.

Prusty, Deeptimayee; Mansingh, Sriram; Acharya, Lopamudra; Paramanik, Lekha; Parida, K. M.

doi: 10.1039/d1ra08004kpmid: 35425155

Designing promising photocatalytic systems with wide photon absorption and better exciton separation ability is a cutting-edge technology for enhanced solar-light-driven hydrogen production. In this context, non-stoichiometric Cu0.75In0.25S nanocrystals (CIS NCs) coupled with three-dimensional (3D) BiOI micro-flowers (BOI MFs) were synthesized through an ultra-sonication strategy forming a CIS–BOI heterojunction, which was well supported by XRD, photocurrent, XPS and Mott–Schottky analyses. Further, the co-catalyst-free CIS–BOI binary hybrid shows improved hydrogen evolution, i.e., 588.72 μmol h−1, which is 3.2 times greater than the pristine CIS NC (183.97 μmol h−1). Additionally, the binary composite confers an apparent conversion efficiency (ACE) of 9.44% (8.90 × 1016 number of H2 molecule per sec), which is extensively attributed to the robust charge carrier separation and transfer efficiency via the direct Z-scheme mechanism (proved through superoxide and H2 evolution activity). Moreover, the broad photon absorption range and productive exciton separation over the CIS–BOI composite are substantially justified by UV-Vis DRS, PL, EIS and photocurrent measurements.

Afzal, Amir Muhammad; Iqbal, Muhammad Zahir; Iqbal, Muhammad Waqas; Alomayri, Thamer; Dastgeer, Ghulam; Javed, Yasir; Shad, Naveed Akhter; Khan, Rajwali; Sajid, M. Munir; Neffati, R.; Abbas, Tasawar; Khan, Qudrat Ullah

doi: 10.1039/d1ra07276epmid: 35425203

Transition metal dichalcogenides (TMDs) have received significant attention owing to their thickness-dependent folded current–voltage (Ids–Vds) characteristics, which offer various threshold voltage values. Owing to these astonishing characteristics, TMDs based negative differential resistance (NDR) devices are preferred for the realization of multi-valued logic applications. In this study, an innovative and ground-breaking germanium selenide/hafnium disulfide (p-GeSe/n-HfS2) TMDs van der Waals heterostructure (vdWH) NDR device is designed. An extraordinary peak-to-valley current ratio (≈5.8) was estimated at room temperature and was used to explain the tunneling and diffusion currents by using the tunneling mechanism. In addition, the p-GeSe/n-HfS2 vdWH diode was used as a ternary inverter. The TMD vdWH diode, which can exhibit different band alignments, is a step forward on the road to developing high-performance multifunctional devices in electronics.

Senthilkumar, P.; Mohapatra, Mamata; Basu, Suddhasatwa

doi: 10.1039/d1ra05062apmid: 35425201

The economic viability of CO2 reactors is contingent on the selectivity of the CO2 reduction reaction and the rate of product formation. For this, the rational design of electrolyzers also has a substantial impact on the figures of merit (current density, faradaic efficiency, cell durability). Thus, herein we portray a short review on the shortcomings, challenges and the recent developments on different reactor configurations, components and membrane structures for the efficient electrochemical CO2 reduction (CO2R) into HCOO−/HCOOH. Despite their low CO2 solubility and poor mass transport, H-type electrolyzers are commercialized due to their screening of a vast number of catalysts. In contrast, membrane-based gas and liquid phase flow reactors break the barriers faced by H-types through the incorporation of gas diffusion electrodes (GDEs) and the membrane electrode assembly (MEA). As the GDE forms the gas–liquid–solid interface, it allows the electrolyzers to generate current densities at the industrial level (200 mA cm−2). Intriguingly, a continuous liquid fed intermittent flow electrolyzer can control the electrolyte flow at a desired frequency and allow sufficient time for CO2 gas molecules to effectively reduce into HCOOH. Therefore, a high and stable faradaic efficiency (95%) is achieved in 4 h for HCOOH (576.98 mg) using the boron-doped diamond catalyst. Very recently, a novel strategy to enhance the CO2R to HCOO−/HCOOH has been adopted via the recirculation of by-products to the liquid phase MEA flow reactors, which substantially improves HCOO− selectivity, lowers material costs, and promotes CO2 mass transfer. In the end, the zero-gap electrolyzer has newly emerged and affords reduced ohmic losses, leading to a straight-forward implementation of industrial systems for CO2R to value-added products in the future. Besides, the efficiency of HCOO−/HCOOH production is also explored against proton exchange, anion exchange and bipolar membranes, and the pH of the electrolyte plays a dominant role in deciding the stability and characteristics of the membranes. It is also depicted that the product selectivity depends on different electrolyzer configurations. Recently, bimetallic alloys (Bi–Sn, Bi–In) and 2D layered composites (SnO2/rGO/CNT) have proven to be potential electrocatalysts (faradaic efficiency > 95%, highly selective and durable) assigned to the abundant active sites for CO2R. Based on the recent findings and future research directions, we draw reader's attention to construct economic, scalable and energy-efficient CO2R electrolyzers to realize the techno-economic predictions.

Ichihashi, Kotoe; Umezawa, Masakazu; Ueya, Yuichi; Okubo, Kyohei; Takamoto, Eiji; Matsuda, Takashi; Kamimura, Masao; Soga, Kohei

doi: 10.1039/d1ra08330apmid: 35425212

Over-thousand-nanometer (OTN) near-infrared (NIR) fluorophores are useful for biological deep imaging because of the reduced absorption and scattering of OTN-NIR light in biological tissues. IR-1061, an OTN-NIR fluorescent dye, has a hydrophobic and cationic backbone in its molecular structure, and a non-polar counter ion, BF4−. Because of its hydrophobicity, IR-1061 needs to be encapsulated in a hydrophobic microenvironment, such as a hydrophobic core of polymer micelles, shielded with a hydrophilic shell for bioimaging applications. Previous studies have shown that the affinity of dyes with hydrophobic core polymers is dependent on the polarity of the core polymer, and that this characteristic is important for designing dye-encapsulated micelles to be used in bioimaging. In this study, the dye–polymer affinity was investigated using hydrophobic polymer films with different chiral structures of poly(lactic acid). IR-1061 showed higher affinity for L- and D-lactic acid copolymers (i.e., poly(DL-lactic acid) (PDLLA)) than to poly(L-lactic acid) (PLLA), as IR-1061 shows less dimerization in PDLLA than in PLLA. In contrast, the stability of IR-1061 in PDLLA was less than that in PLLA due to the influence of hydroxyl groups. Choosing hydrophobic core polymers for their robustness and dye affinity is an effective strategy to prepare OTN-NIR fluorescent probes for in vivo deep imaging.

Ghasemi-Ghahsareh, Aref; Safaei-Ghomi, Javad; Oboudatian, Hourieh Sadat

doi: 10.1039/d1ra07654jpmid: 35425168

In this work, L-tryptophan functionalized silica-coated magnetic nanoparticles were readily prepared and evaluated as a recyclable magnetic nanocatalyst for the synthesis of spiro[indene-2,2′-naphthalene]-4′-carbonitrile derivatives through the one-pot four-component reaction of malononitrile, cyclohexanone, aromatic aldehydes, and 1,3-indandione. This novel magnetic nanocatalyst was confirmed to be effective and provide products in moderate to excellent yields under reflux conditions. The structure of obtained nanoparticles was characterized using FT-IR, XRD, VSM, EDX, elemental mapping, FE-SEM, and TGA. This synthetic protocol provides several benefits such as excellent yields in short reaction times (64–91%), saving costs, reusability of the catalyst using an external magnet (seven runs), and low catalyst loading.

Jebasty, R. Mariyal; Sjåstad, Anja Olafsen; Vidya, R.

doi: 10.1039/d0ra08132apmid: 35425181

Materials with an intermediate energy band (IB) introduced in the forbidden gap are viable alternatives to tandem configurations of solar cells for increasing the photon-conversion efficiency. One of the aspiring designs proposed for the intermediate band concept is hyperdoped (Ti, V):In2S3. Being very important in copper indium gallium sulfide (CIGS) solar cells, indium thiospinel (In2S3) is known for its three different temperature as well as pressure, polymorphs. The most stable β-In2S3 was experimentally shown to have an isolated intermediate band (IB) and exhibits sub-band gap absorption due to the completely filled IB after V-doping. Though experimental observation holds a positive signature, recent DFT studies did not show a metallic intermediate band for the V dopant in the 3+ charge state. In order to clarify this, we have taken incentive from experimental XRD analysis that V-doped β-In2S3 shows peaks from disordered In vacancies (either α or γ), in addition to the ordered In vacancies expected. Hence, we have carried out state-of-the-art DFT based computations on pure and Ti, V-doped In2S3 in the γ-phase which has not been studied yet. We considered the Ti and V dopants in various charge states. Our theoretical study including hybrid functional, does in fact find the IB in V-doped γ-In2S3. However, at equilibrium the IB lies in between the Fermi level (EF) and conduction band minimum (CBM).

Zhang, Shuaibo; Li, Haixia; Zhang, Anchao; Sun, Zhijun; Zhang, Xinmin; Yang, Changze; Jin, Leying; Song, Zhiheng

doi: 10.1039/d1ra08800apmid: 35425210

MnxZr1 series catalysts were prepared by a coprecipitation method. The effect of zirconium doping on the NH3-SCR performance of the MnOx catalyst was studied, and the influence of the calcination temperature on the catalyst activity was explored. The results showed that the Mn6Zr1 catalyst exhibited good NH3-SCR activity when calcined at 400 °C. When the reaction temperature was 125–250 °C, the NOx conversion rate of Mn6Zr1 catalyst reached more than 90%, and the optimal conversion efficiency reached 97%. In addition, the Mn6Zr1 catalyst showed excellent SO2 and H2O resistance at the optimum reaction temperature. Meanwhile, the catalysts were characterized. The results showed that the morphology of the MnOx catalyst was significantly changed, whereby as the proportion of Mn4+ and Oα species increased, the physical properties of the catalyst were improved. In addition, both Lewis acid sites and Brønsted acid sites existed in the Mn6Zr1 catalyst, which reduced the reduction temperature of the catalyst. In summary, zirconium doping successfully improved the NH3-SCR performance of MnOx.