Shape Controlled Synthesis of Copper Vanadate Platelet Nanostructures, Their Optical Band Edges, and Solar-Driven Water Splitting Properties

Abstract

We report the morphological and size tailored rational and facile synthesis of copper vanadate nanostructures via sonication assisted sol gel method. Field emission scanning electron microscopy (FESEM), indicated irregular and nanoflakes morphologies for the as synthesized copper vanadate (CV-120) and copper vanadate calcined at 250 °C (CV-250). The semispherical platelets shaped morphology revealed for the copper vanadate calcined at 550 °C (CV-500). The XRD patterns confirm the monoclinic and triclinic crystal phases for CV-250 and CV-500, respectively. The optical properties of CV-250 and CV-500 via UV-DRS showed significant absorption in the visible regime at λ = 565 nm and 670 nm with band gap 2.2 eV and 1.84 eV, respectively as calculated from Kubelka-Munk (KM) equation via Tauc’s plot. The values of band edge positions of CV-250 and CV-550 straddle with the hydrogen (HER) and oxygen evolution reaction (OER) potentials. The photoelectrodes of CV-250 and CV-500 fabricated by adsorption desorption method to test their photoelectrochemical (PEC) water splitting performance in the three-electrode cell. The onset photocurrent potential is observed at ~0.42 V, which reached to saturation at 1.05 V. The photocurrent density at saturation is ~0.65 mA/cm2 for CV-250 and CV-500, respectively.

Chemical transformations at the nanoscale: nanocrystal-seeded synthesis of β-Cu2V2O7 with enhanced photoconversion efficiencies

“…3 and S4 † ). Next to the complexity of the CuO–V 2 O 5 phase diagram itself, 17 – 25 the XRD data analysis was complicated by a number of factors, such as the close similarity of the lattice parameters of different phases and the resulting peak overlap, the significant line broadening associated with grain sizes smaller than 100 nm and the potential preferred orientation of the grains on the substrate. Quantitative Rietveld refinement was performed to analyze the phase composition of the synthesized samples (Table S1 and Fig.…”

“… 17 – 23 In previous studies, the high annealing temperatures above 450 °C have resulted in grain sizes varying from 200 nm to 1 μm. 17 – 25 These grain sizes are much larger than the charge carrier diffusion length (20–40 nm), which may be among the causes for the low photocurrent density in these studies. 22 Thus, synthesizing copper vanadates with monodisperse grain sizes ≤40 nm is expected to improve the photoconversion efficiency of this promising material.…”

“… 14 There are 26 phases of copper vanadate listed in the Inorganic Crystal Structure database with different structural and opto-electronic properties. Various techniques like solid state synthesis, 15 , 16 solution approaches, 17 – 20 physical vapor deposition, 21 – 23 electrospraying, 24 sol–gel methods 25 have been applied to access different crystalline phases within this family of compounds.…”

Recent Developments in Nanostructured Palladium and Other Metal Catalysts for Organic Transformation

“…Khan and Qurashi synthesized highly controlled platelet-shaped copper vanadate nanocatalysts for PEC water splitting and compared the results with NPs of conventional shape. It was determined that the shape-controlled copper vanadate enhanced the light trapping properties of the catalyst and hence enhanced the photoelectrochemical performance of the catalyst [25]. Similarly, shape-controlled NPs are also found useful in organic conversion to some extent.…”

Facile synthesis of high yield two dimensional zinc vanadate nanoflakes

“…Pei et al [33,34] represent a controlled synthesis of calcium vanadate. Recently, few reported researches have been focused on facile synthesis of metal vanadate by different methods for example; Khan and Qurashi [18] reported a facile synthesis of copper vanadate nanostructures via sonication assisted sol gel method. Mohammad Reza Mosleh has synthesized FeVO 4 by a facile morphology control in presence of different surfactants [30].…”