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To elucidate the visible-light photocatalytic mechanism and performance of Ag- and Pd-modified TiO2 for the degradation of sulfur-containing 2-mercaptobenzothiazole.

August 16, 2026Next Materials0 citationsOpen Access

Elucidating the role of noble metals in Ag- and Pd-modified TiO2 visible-light photocatalysts: Theoretical validation of experimental evidence

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MNManaswita NagNational Aerospace Laboratories GPGanga PeriyasamyBangalore University CRChaitra RaviBangalore University

Key Points

To elucidate the visible-light photocatalytic mechanism and performance of Ag- and Pd-modified TiO2 for the degradation of sulfur-containing 2-mercaptobenzothiazole.
Synthesized Ag- and Pd-modified TiO2 nanoparticles and nanotubes, characterizing their structural, optical, and electronic properties via Tauc plots, X-ray photoelectron spectroscopy, and photoluminescence.
Assessed photocatalytic degradation of 2-mercaptobenzothiazole under visible light and conducted density functional theory calculations to model adsorption and electron transfer dynamics.
Band gap values decreased from 3.21 eV in pristine TiO2 to 2.93 eV in Ag-modified TiO2 and 2.45 eV in Pd-modified TiO2, with Ag-modified TiO2 displaying surface plasmon resonance at 420–426 nm.
Ag-modified TiO2 nanoparticles achieved 99% degradation of 2-mercaptobenzothiazole following pseudo-first-order kinetics, substantially outperforming pristine TiO2 and Degussa P25.
Density functional theory calculations confirmed enhanced pollutant adsorption, robust Ag-TiO2 interfacial interactions, and defect-assisted charge transfer driven by Ti3+ species and oxygen vacancies.

Abstract

A combined experimental–theoretical understanding of the noble metal-modified TiO 2 photocatalysis for environmental remediation remains relatively unexplored. This study investigates the influence of silver (Ag) and palladium (Pd) modifications on the visible-light photocatalytic performance of nanosized TiO 2 for the degradation of the sulfur-containing pollutant 2-mercaptobenzothiazole (2-MBT), and correlates experimental findings with density functional theory (DFT) calculations. Structural and spectroscopic analysis of the synthesized Ag- and Pd- modified TiO 2 (AgT and PdT) nanoparticles (NP) and nanotubes (NT) confirmed phase-pure anatase-TiO 2 NP (T NP) and low crystalline titanate NT (T NT), respectively, with uniformly distributed Ag and Pd. Tauc plots revealed enhanced visible-light absorption, with band gaps decreasing from 3.21 to 2.93 and 2.45 eV, for pristine TiO 2, AgT, and PdT, respectively. AgT additionally exhibited a surface plasmon resonance (SPR) band at 420–426 nm. X-ray photoelectron spectroscopy (XPS) identified Ag predominantly as Ag + (Ag 2 O) and Pd mainly as Pd 0 with minor Pd 2+ , while Ti 3+ species and oxygen vacancies were observed in AgT, indicating defect-assisted charge separation, further supported by pronounced photoluminescence (PL) quenching. Photocatalytic studies demonstrated substantially enhanced 2-MBT degradation with noble metal modification compared with pristine TiO 2 and Degussa P25, with AgT NP achieving 99% degradation following pseudo-first-order kinetics. DFT calculations validate experimental results, revealing stronger 2-MBT adsorption, enhanced Ag-TiO 2 interfacial interactions, and improved electron transfer in AgT. The combined experimental-theoretical study correlating structure–property–activity relationships establishes Ag-modified TiO 2 as a promising visible-light photocatalyst for sulfur pollutant remediation.

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Elucidating the role of noble metals in Ag- and Pd-modified TiO2 visible-light photocatalysts: Theoretical validation of experimental evidence

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