Starch-concentration-controlled growth of anisotropic bismuth nanoplates: a facile and bio-assisted aqueous route to morphology-tuned optical response
- 1Chemistry Discipline, Khulna University Khulna-9208 Bangladesh [email protected].
- 2Department of Applied Chemistry, Chemical Engineering, and Biochemical Engineering, Graduate School of Science and Engineering, Yamagata University Yonezawa Yamagata 992-8510 Japan [email protected].
Abstract
Herein, we report a bio-assisted aqueous synthesis of single-crystalline, anisotropic bismuth (Bi⁰) nanoplates using starch as a dual reductant/kinetic regulator and poly(vinylpyrrolidone) (PVP) as a facet-selective capping agent. Powder XRD confirms the formation of rhombohedral elemental bismuth (JCPDS Card No. 44-1246) with no detectable crystalline impurity phases. Systematic evaluation of synthesis parameters reveals a surface-energy-driven growth mechanism governed by a kinetic and capping interplay. Lower starch concentrations produce predominantly quasi-spherical nanoparticles (∼80 nm) alongside minor polyhedral structures, whereas higher starch feeds favor the formation of uniform hexagonal nanoplates with lateral diagonal dimensions of 145-240 nm. Concurrently, lower PVP feeds result in mixed morphologies containing irregular nanoplates (∼115 nm), whereas increasing the PVP feed promotes effective facet passivation, increasing the prevalence of uniform hexagonal nanoplates (120-145 nm). Time-dependent observations show an initial stage at 2 h consisting of a mixed morphology (∼145 nm) that progresses beyond 2 h into predominantly uniform hexagonal nanoplates (∼200 nm), exhibiting a visibly increased thickness plates at 24 h consistent with Ostwald ripening coupled with facet-selective capping. This structural transition induces a prominent bathochromic shift in the localized surface plasmon resonance (LSPR) from 410 nm to ∼600 nm, driven by 2D shape anisotropy and in-plane dipolar modes. Spectroscopic (FTIR) and thermal (TGA) characterizations confirm dual-polymer surface stabilization, where starch binds via hydroxyl hydrogen bonding (redshifted from 3380 cm⁻¹ to 3290 cm⁻¹) and PVP undergoes physical adsorption (1655 cm⁻¹ C[double bond, length as m-dash]O stretch), imparting high aqueous dispersion stability (-50 mV zeta potential). This study provides quantitative mechanistic insights into the green, shape-controlled synthesis of functional bismuth nanostructures for potential optoelectronic, thermoelectric, and photothermal applications.
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BibTeX
@article{mahiuddin2026starchconcentrationcontrolled,
title = {{Starch-concentration-controlled growth of anisotropic bismuth nanoplates: a facile and bio-assisted aqueous route to morphology-tuned optical response}},
author = {Md Mahiuddin and Prianka Saha and Bungo Ochiai},
journal = {RSC advances},
year = {2026},
month = oct,
doi = {10.1039/d6ra08893g},
url = {https://europepmc.org/article/PMC/PMC13718629},
note = {CC BY},
}
RIS
TY - JOUR
TI - Starch-concentration-controlled growth of anisotropic bismuth nanoplates: a facile and bio-assisted aqueous route to morphology-tuned optical response
AU - Md Mahiuddin
AU - Prianka Saha
AU - Bungo Ochiai
PY - 2026
DA - 2026/10/29
JO - RSC advances
DO - 10.1039/d6ra08893g
UR - https://europepmc.org/article/PMC/PMC13718629
AB - Herein, we report a bio-assisted aqueous synthesis of single-crystalline, anisotropic bismuth (Bi⁰) nanoplates using starch as a dual reductant/kinetic regulator and poly(vinylpyrrolidone) (PVP) as a facet-selective capping agent. Powder XRD confirms the formation of rhombohedral elemental bismuth (JCPDS Card No. 44-1246) with no detectable crystalline impurity phases. Systematic evaluation of synthesis parameters reveals a surface-energy-driven growth mechanism governed by a kinetic and capping interplay. Lower starch concentrations produce predominantly quasi-spherical nanoparticles (∼80 nm) alongside minor polyhedral structures, whereas higher starch feeds favor the formation of uniform hexagonal nanoplates with lateral diagonal dimensions of 145-240 nm. Concurrently, lower PVP feeds result in mixed morphologies containing irregular nanoplates (∼115 nm), whereas increasing the PVP feed promotes effective facet passivation, increasing the prevalence of uniform hexagonal nanoplates (120-145 nm). Time-dependent observations show an initial stage at 2 h consisting of a mixed morphology (∼145 nm) that progresses beyond 2 h into predominantly uniform hexagonal nanoplates (∼200 nm), exhibiting a visibly increased thickness plates at 24 h consistent with Ostwald ripening coupled with facet-selective capping. This structural transition induces a prominent bathochromic shift in the localized surface plasmon resonance (LSPR) from 410 nm to ∼600 nm, driven by 2D shape anisotropy and in-plane dipolar modes. Spectroscopic (FTIR) and thermal (TGA) characterizations confirm dual-polymer surface stabilization, where starch binds via hydroxyl hydrogen bonding (redshifted from 3380 cm⁻¹ to 3290 cm⁻¹) and PVP undergoes physical adsorption (1655 cm⁻¹ C[double bond, length as m-dash]O stretch), imparting high aqueous dispersion stability (-50 mV zeta potential). This study provides quantitative mechanistic insights into the green, shape-controlled synthesis of functional bismuth nanostructures for potential optoelectronic, thermoelectric, and photothermal applications.
SN - 2046-2069
ER -