New ligand engineering strategy creates more active nanocluster catalysts

When toxic carbon monoxide gas drifts into the air we breathe, it can be deadly. That's why scientists in Sendai, Japan, have built something that could help clean it from the air more easily than ever before — a tiny particle smaller than a dust mite, yet smart enough to break down this invisible threat at much lower temperatures than existing tools.

A team from Tohoku University, working with researchers from Tokyo University of Science, Tokyo Metropolitan University, and the Japan Fine Ceramics Center, designed a new kind of catalyst, which is a material that speeds up chemical reactions. Their creation — an ultra-small gold-platinum particle called [Au₂₄Pt(TBBT)₁₂(TDT)₃]⁰ — managed to break down carbon monoxide, or CO, at temperatures 39 degrees Celsius lower than before.

The challenge the team faced sounds simple but is actually quite tricky. These tiny particles need a protective outer layer of molecules called ligands to stay stable. Without that protection, they fall apart. But those same protective layers also block the active spots where the chemical reaction should happen — like having a locked door when you need people to walk through. Previous attempts to remove the ligands required high heat, which often damaged the particles or left behind messy residue.

The researchers found a clever workaround. They kept some of the weaker ligands but reinforced the particle's outer framework by threading dithiolate molecules through them like stitching. This made the particle stable enough to handle, while still letting the weaker ligands slide off more easily when heated. The result was a catalyst that worked better without needing to be pushed to extreme temperatures.

When supported on cerium oxide and given a simple pretreatment, the new particle cut the temperature needed to convert half of the carbon monoxide by 39°C compared to a standard version. The team published their findings in the journal Nano Letters.

The implications stretch beyond just cleaning carbon monoxide. The researchers say their ligand-engineering approach could be applied to other nanocluster catalysts, potentially making industrial chemical processes more energy-efficient overall. Fewer degrees needed means less energy burned, which means less pollution created in the first place.