A multinational team including researchers from Tohoku University has pioneered a breakthrough in catalyst design by developing gold-platinum (Au₂₄Pt) alloy nanoclusters with advanced ligand engineering to optimize low-temperature carbon monoxide (CO) oxidation. This significant advance addresses the longstanding trade-off between ligand-induced nanocluster stability and catalytic activity.
Traditional Au₂₄Pt nanoclusters use thiolate ligands to stabilize their atomic structures, but these ligands block access to the active metal sites necessary for efficient catalytic reactions. Attempts to weaken ligand binding to expose these sites greatly reduce nanocluster stability, causing aggregation and loss of catalytic function. Overcoming these limitations, the research team introduced dithiolate (SR’S) bridging ligands alongside weaker monothiolates, creating a reinforced “staple” framework that maintains structural integrity while facilitating ligand removal at lower temperatures.
The engineered nanocluster, denoted [Au₂₄Pt(TBBT)₁₂(TDT)₃]⁰, integrates relatively weakly bound 4-tert-butylbenzenethiolate (TBBT) ligands with thiodithiolate (TDT) groups that bridge staples around the metal core. This architecture is designed to promote the selective detachment of TBBT ligands at reduced thermal input, preserving the dithiolate framework and the precise atomic arrangement of the cluster. Mass spectrometry analysis confirmed this selective bond cleavage, demonstrating a controlled ligand dissociation mechanism critical for catalyst activation.
When deposited on cerium oxide (CeO₂) as a support at just 0.5 wt%, the modified nanoclusters exhibited remarkable catalytic performance. The catalyst activated CO oxidation at significantly lower temperatures compared to the conventional [Au₂₄Pt(PET)₁₈]⁰ system, beginning reaction onset at 215 °C versus 236 °C without pretreatment. Following oxidative pretreatment at 250 °C, the novel catalyst lowered the temperature for 50% CO conversion by a striking 39 °C, evidencing enhanced accessibility of active sites and improved overall activity.
This achievement harnesses ligand engineering to circumvent the typical compromise between catalyst stability and reactivity. By reinforcing the nanocluster’s staple motifs with dithiolate linkers, the researchers enabled the strategic incorporation of weaker gold-sulfur bonds crucial for facile ligand removal, all while preserving the atomically precise geometry essential for catalytic function.
These findings open new avenues for designing highly active, durable supported metal nanoclusters. The methodology enables easy catalyst activation through mild pretreatment conditions, reducing aggregation risks and sulfur residue contamination that have limited previous systems. Future research will explore how variations in ligand desorption pathways influence catalyst structure and performance during real-time catalytic processes.
Published in the journal Nano Letters, this work represents a pivotal step toward finely tuned nanocatalysts with enhanced low-temperature activity, heralding significant implications for pollution control and energy conversion technologies.
Subject of Research: Catalyst design, metal nanoclusters, ligand engineering, low-temperature CO oxidation
Article Title: Ligand Engineering of Dithiolate-Protected Au24Pt Nanoclusters for Improved Thermocatalytic Activity
News Publication Date: June 29, 2026
Web References: http://dx.doi.org/10.1021/acs.nanolett.6c01977
Image Credits: Tohoku University
Keywords
Chemistry, Nanoclusters, Alloys, Ligands
