# Enhancing the Catalytic Performance of PdNPs for Cr(VI) Reduction by Increasing Pd(0) Content

## TL;DR

This paper shows that increasing the Pd(0) content in palladium nanoparticles improves their ability to reduce toxic Cr(VI) in the environment.

## Contribution

The study identifies Pd(0) content as a key factor in catalytic performance for Cr(VI) reduction using fungal-based catalysts.

## Key findings

- Pd(0) content ranged from 6.4% to 59.2% depending on the chemical treatment used.
- The NCPdSF sample achieved the highest Cr(VI) reduction due to its high Pd(0) content.
- Functional groups like phosphate and amine play important roles in Pd binding and reduction.

## Abstract

Hexavalent chromium [Cr(VI)] is a hazardous environmental contaminant, and palladium nanoparticles (PdNPs) have shown promise as catalysts for its reduction. This study explores the primary factor influencing the catalytic performance of PdNPs in Cr(VI) reduction by investigating the crystal structure and composition of PdNPs in fungal-based catalysts. Five Pd-loaded catalysts were synthesized by treating fungal biomass with different chemical reagents, resulting in varying Pd(0) contents. The nanoparticle morphology, chemical states, and functional group interactions during Pd adsorption and reduction were investigated using multiple analytical techniques. The results showed that fungal hyphae remained structurally intact throughout the treatment process. PdNPs smaller than 2 nm were observed, with both Pd(0) and PdO present. The proportion of Pd(0) ranged from 6.4% to 37.2%, depending on the chemical reagent used. In addition, functional groups such as phosphate, amine, hydroxyl, and carboxyl were found to play key roles in palladium binding, underscoring the importance of surface chemistry in the adsorption and reduction process. A strong positive correlation was observed between the Pd(0) content and catalytic activity. Notably, the NCPdSF sample (palladium-loaded biomass treated with sodium formate) exhibited the highest Pd(0) content of 59.2% and achieved the most effective Cr(VI) reduction. These results suggest that Pd(0) content is a key determinant of catalytic efficiency in Cr(VI) reduction and that optimizing chemical treatments to enhance Pd(0) levels can substantially improve catalyst performance.