Complex Salts and Nanoparticles in Catalytic Systems

Complex salts and metal nanoparticles have emerged as pivotal components in heterogeneous catalysis, combining the structural versatility of ionic frameworks with the high surface‐to‐volume ratio of nanoscale metals. Complex salts, often comprising transition‐metal centres coordinated by organic or inorganic ligands, can furnish unusual redox properties and tunable acid–base character. When integrated with nanoparticles, these salts may stabilise active sites, promote synergistic interactions and foster selectivity in reactions ranging from hydrogen evolution to oxygen reduction. Advances in synthetic control, supported by in situ characterisation, have illuminated how particle size, shell composition and electronic perturbations govern catalytic performance. The interplay between ligand fields in complex salts and the d‐band structure of nanoparticles underpins many of the observed rate enhancements and offers pathways to durable, scalable catalytic materials with broad industrial and environmental applications.

Research from Nature Portfolio

Recent studies have applied high‐resolution valence‐to‐core X‐ray emission spectroscopy to Pt–Ni alloy nanoparticles, revealing how lattice strain and ligand interactions compete to shift the d-band centre relative to the Fermi level. Experimental data indicate that compressive strain can widen the d-band in Pt₃Ni and PtNi, whereas dilution by Ni in PtNi₃ leads to d-band narrowing as ligand effects dominate. These insights clarify the electronic origins of enhanced activity in oxygen reduction and inform the rational design of bimetallic catalysts with optimised electronic structures.

Complex Salts and Nanoparticles in Catalytic Systems publication trend

The graph below shows the total number of articles in complex salts and nanoparticles in catalytic systems across all publications each year (not limited to Nature Index journals).

Technical terms

Complex salt: A compound in which a central metal ion is coordinated by one or more ligands, forming an anionic or cationic complex within a salt lattice.

Nanoparticle: A solid particle with dimensions typically in the 1–100 nm range, exhibiting size-dependent physicochemical properties.

d-band centre: The weighted average energy of metal d-electron states relative to the Fermi level, influencing adsorption and catalytic activity.

Core–shell nanoparticle: A composite structure in which a central “core” material is encapsulated by an outer “shell” layer, often of a different composition.

Ligand effect: Modification of a metal’s electronic structure due to interactions with neighbouring atoms or molecular ligands bound to its surface.

Strain effect: Alteration of electronic and catalytic properties caused by lattice distortion induced by size mismatch or alloying.

Valence-to-core X-ray emission spectroscopy: A technique that probes valence-band states by measuring X-ray emission following core-level excitation, revealing detailed electronic structure.

Catalytic activity: The capacity of a material to accelerate a chemical reaction, often quantified by turnover frequency or conversion efficiency.

References

1. Electronic behaviour of Au-Pt alloys and the 4f binding energy shift anomaly in Au bimetallics- X-ray spectroscopy studies. AIP Advances (2018).
2. How to Determine the Core-Shell Nature in Bimetallic Catalyst Particles?. Catalysts (2014).
3. PtRu Nanoparticles Deposited by the Sulfite Complex Method on Highly Porous Carbon Xerogels: Effect of the Thermal Treatment. Catalysts (2013).
4. Strain and ligand effects in Pt-Ni alloys studied by valence-to-core X-ray emission spectroscopy. Scientific Reports (2021).