Despite the noteworthy progress made in the nanotubular architectures with well-de ned lengths and diameter, the synthesis of a purely covalent bonded organic nanotube, so far, proved to be elusive. Our work includes a hitherto unavailable structure, "Covalent Organic Nanotubes (CONTs)," to the repertoire. Strong covalent bonds between C, N, and O imparts high thermal and chemical stability of CONTs. This novel bottom-up approach provides an edge over the carbon nanotubes (CNTs) in functionalization, synthetic conditions, and porosity. CONT-1 exhibits a BET surface area of 321 m2g-1. These exible CONTs intertwine with each other. The computational studies establish the role of solvent as the critical driving force for this type of convolution. Upon ultrasonication, the intertwined CONT-1 coil to form the toroidal superstructure.

Piezocatalytic water splitting is an emerging approach to generate "green hydrogen" that can address several drawbacks of photocatalytic and electrocatalytic approaches. However, existing piezocatalysts are few and with minimal structural flexibility for engineering properties. Moreover, the scope of utilizing unprocessed water is yet unknown and may widely differ from competing techniques due to the constantly varying nature of surface potential. Herein, we present Bi 4 TaO 8 Cl as a representative of a class of layered perovskite oxyhalide piezocatalysts with high hydrogen production efficiency and exciting tailorable features including the layer number, multiple cation−anion combination options, etc. In the absence of any cocatalyst and scavenger, an ultrahigh production rate is achievable (1.5 mmol g −1 h −1 ), along with simultaneous generation of value-added H 2 O 2 . The production rate using seawater is somewhat less yet appreciably superior to photocatalytic H 2 production by most oxides as well as piezocatalysts and has been illustrated using a double-layer model for further development.

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Clean water is a fundamental human right but millions struggle for it daily. Herein, we demonstrate a new piezophotocatalyst with immense structural diversity for universal wastewater decontamination. Single-crystalline Bi 4 TaO 8 Cl nanoplates with exposed piezoelectric facets exhibit visible-light response, piezoelectric behavior with coercive voltages of ±5 V yielding 0.35% crystal deformation, and pressure-induced band-bending of >2.5 eV. Using five common contaminants of textile and pharmaceutical industries, we show that the nanoplates can mineralize them in all piezocatalytic, photocatalytic, and piezo-photocatalytic approaches with efficiencies higher than most catalysts developed for just one contaminant. Their efficiencies for feedstocks differing over 2 orders of magnitude in concentrations, the highest to date, are also demonstrated to simulate real-life situations. These extensive studies established that combining piezocatalytic and photocatalytic approaches can lead to a tremendous synergy exceeding >45%. The origin of synergy has been illustrated for the first time using band-bending models and improved charge transfer from valence and conduction band electronic surfaces. We further quantified synergy across reactants, concentrations, and ultrasonic frequency and power to demonstrate their versatility and unpredictability. Finally, seven parameters that contribute to synergy but create unpredictability have been identified for the rational design of piezo-photocatalysts for wastewater treatment.

2D van der Waals heterostructure paves a path towards next generation semiconductor junctions for nanoelectronics devices in the post silicon era. Probing the band alignment at a real condition of such 2D contacts and experimental determination of its junction parameters is necessary to comprehend the charge diffusion and transport through such 2D nano-junctions. Here, we demonstrate the formation of the p-n junction at the MoS2/Black phosphorene (BP) interface and conduct a nanoscale investigation to experimentally measure the band alignment at real conditions by means of measuring the spatial distribution of built-in potential, built-in electric field, and depletion width using the Kelvin probe force microscopy (KPFM) technique. We show that optimization of lift scan height is critical for defining the depletion region of MoS2/BP with nanoscale precision using the KPFM technique. The variations in the built-in potential and built-in electric field with varying thicknesses of MoS2 are revealed and calibrated.