Photocatalytic activity of MnTiO3 perovskite nanodiscs for the removal of organic pollutants

MTO nanodiscs synthesized using the hydrothermal approach were explored for the photocatalytic removal of methylene blue (MB), rhodamine B (RhB), congo red (CR), and methyl orange (MO). The disc-like structures of ~16 nm thick and ~291 nm average diameter of stoichiometric MTO were rhombohedral in nature. The MTO nanodiscs delivered stable and recyclable photocatalytic activity under Xe lamp irradiation. The kinetic studies showed the 89.7, 80.4, 79.4, and 79.4 % degradation of MB, RhB, MO, and CR at the rate constants of 0.011(±0.001), 0.006(±0.001), 0.007(±0.0007), and 0.009 (±0.0001) min−1, respectively, after the 180 min of irradiation. The substantial function of photogenerated holes and hydroxide radicals pertaining to the dye removal phenomena is confirmed by radical scavenger trapping studies. Overall, the present studies provide a way to develop pristine and heterostructure perovskite for photocatalysts degradation of various organic wastes

Atomic layer deposited-ZnO@3D-Ni-foam composite for Na-ion battery anode: A novel route for easy and efficient electrode preparation

The sluggish kinetics of relatively larger Na-ion still limits the performance of sodium-ion batteries (SIBs) as compared to lithium-ion batteries (LIBs). In this context, a novel route is introduced by coating a thin films of ZnO on a porous 3D Ni-foam scaffold by atomic layer deposition (ALD) for the first time and is used as a superior anode for SIBs without any post-modifications. The scanning electron microscopy along with transmission electron microscopy studies reveal that highly crystalline ZnO can be deposited on such complex 3D Ni-foam with excellent uniformity and conformality. A stable reversible capacity of similar to 65.1 mAh g(-1) up to 400 charge discharge cycles and the excellent rate capability in a wide current density range (30-1000 mA g(-1)) establish the potential of this composite prepared by a direct and relatively easier method of electrode fabrication. The predominant alloying-dealloying based reactions for Zn-based anode material is also established in SIBs by the post-cycling X-ray photoelectron spectroscopic analyses. The post-cycling analysis of these anodes also reveals the robust structure with good adhesion of the ALD grown films on Ni-foam. In addition, similar study on 2D substrate elucidates the extra advantages of this current strategy. This model efficient route can easily be extended and adopted for any other materials to further enhance the performance of SIBs in future

Revealing the Simultaneous Effects of Conductivity and Amorphous Nature of Atomic‐Layer‐Deposited Double‐Anion‐Based Zinc Oxysulfide as Superior Anodes in Na‐Ion Batteries

Although sodium-ion batteries (SIBs) are considered promising alternatives to their Li counterparts, they still suffer from challenges like slow kinetics of the sodiation process, large volume change, and inferior cycling stability. On the other hand, the presence of additional reversible conversion reactions makes the metal compounds the preferred anode materials over carbon. However, conductivity and crystallinity of such materials often play the pivotal role in this regard. To address these issues, atomic layer deposited double-anion-based ternary zinc oxysulfide (ZnOS) thin films as an anode material in SIBs are reported. Electrochemical studies are carried out with different O/(O+S) ratios, including O-rich and S-rich crystalline ZnOS along with the amorphous phase. Amorphous ZnOS with the O/(O+S) ratio of approximate to 0.4 delivers the most stable and considerably high specific (and volumetric) capacities of 271.9 (approximate to 1315.6 mAh cm(-3)) and 173.1 mAh g(-1) (approximate to 837.7 mAh cm(-3)) at the current densities of 500 and 1000 mA g(-1), respectively. A dominant capacitive-controlled contribution of the amorphous ZnOS anode indicates faster electrochemical reaction kinetics. An electrochemical reaction mechanism is also proposed via X-ray photoelectron spectroscopy analyses. A comparison of the cycling stability further establishes the advantage of this double-anion-based material over pristine ZnO and ZnS anodes

Atomic layer deposited zinc oxysulfide anodes in Li-ion batteries: an efficient solution for electrochemical instability and low conductivity

In addition to their optoelectronic applications, Zn-based oxides and sulfides have also been widely studied as electrode materials in Li-ion batteries owing to their high theoretical capacity. However, both the materials suffer from a drastic loss in capacity due to their poor conductivity and electrochemical instability. A very efficient and carefully controlled combination of these two may address these limitations. In this work, thin films of zinc oxysulfide (ZnOS) with an O/(O + S) ratio of approximate to 0.7 were deposited using a combination of oxide and sulfide atomic layer deposition (ALD) cycles; they were then tested as anodes in Li-ion batteries. The material was grown directly on a stainless steel substrate (SS), characterized extensively using several ex situ characterization tools, and then used as an anode with no binder or conductive additives. Cyclic voltammetry measurements were used to confirm the reversible conversion of ZnOS in addition to the well-known alloying-dealloying Li-Zn reaction. The material loading was further optimized by varying the number of ALD supercycles to attain the maximum stable cycling performance. The highest stable capacities of 632.9 and 510.3 mA h g(-1) were achieved at current densities of 0.1 and 1 A g(-1) (approximate to 4 and 40 A cm(-2)), respectively, for a ZnOS film with an optimum thickness of approximate to 75 nm. The optimized ZnOS anode exhibited superior electrochemical performance in comparison to the equivalent pristine ZnO and ZnS anodes. Finally, the post-cycling analysis of the binder-free ALD grown ZnOS anodes demonstrated excellent adhesion to the SS substrate and the high stability of these films upon cycling

Role of Salt Concentration in Stabilizing Charged Ni-Rich Cathode Interfaces in Li-Ion Batteries.

Publication status: PublishedThe cathode-electrolyte interphase (CEI) in Li-ion batteries plays a key role in suppressing undesired side reactions while facilitating Li-ion transport. Ni-rich layered cathode materials offer improved energy densities, but their high interfacial reactivities can negatively impact the cycle life and rate performance. Here we investigate the role of electrolyte salt concentration, specifically LiPF6 (0.5-5 m), in altering the interfacial reactivity of charged LiN0.8Mn0.1Co0.1O2 (NMC811) cathodes in standard carbonate-based electrolytes (EC/EMC vol %/vol % 3:7). Extended potential holds of NMC811/Li4Ti5O12 (LTO) cells reveal that the parasitic electrolyte oxidation currents observed are strongly dependent on the electrolyte salt concentration. X-ray photoelectron and absorption spectroscopy (XPS/XAS) reveal that a thicker LixPOyFz-/LiF-rich CEI is formed in the higher concentration electrolytes. This suppresses reactions with solvent molecules resulting in a thinner, or less-dense, reduced surface layer (RSL) with lower charge transfer resistance and lower oxidation currents at high potentials. The thicker CEI also limits access of acidic species to the RSL suppressing transition-metal dissolution into the electrolyte, as confirmed by nuclear magnetic resonance (NMR) spectroscopy and inductively coupled plasma optical emission spectroscopy (ICP-OES). This provides insight into the main degradation processes occurring at Ni-rich cathode interfaces in contact with carbonate-based electrolytes and how electrolyte formulation can help to mitigate these