A collaborative research team led by Prof. HUANG Xingjiu from the Hefei Institutes of Physical Science of the Chinese Academy of Sciences (CAS) and Prof. LI Lina from the Shanghai Institute of Applied Physics of CAS, has developed a method to detect harmful heavy metals through a selective catalytic double metal single atom in redox reactions. 

Their research, which combines high-throughput calculation and in situ characterization technology, was recently published in Nano Letters.

"This new method allows us to observe and understand how the bimetallic single-atom catalyst changes while it's working," said Dr. SONG Zongyin, a member of the team. "The catalyst can be used to detect harmful heavy metals in the environment, like copper and arsenic."

Current limitations in spatial and temporal resolution restrict our understanding of atomic-level microscopic dynamics, which hinders the development of catalyst regulation technology and its broader application. To address this, the researchers focused on designing high-performance, sensitive materials for the precise detection of environmental pollutants and body fluid electrolyte ions.

In their study, the researchers integrated advanced in situ synchrotron radiation spectroscopy with high-precision theoretical calculations, enabling real-time capture and analysis of the transient structure of bimetallic single-atom catalysts during catalytic reactions. Through high-throughput screening, they identified an efficient duplex metal atomic electrode interface, which allows for the parallel electrochemical reduction of Cu(II) and As(III).

Further experiments using in situ X-ray absorption fine structure (XAFS) spectroscopy, along with coordination field theory, validated the specific NiCu level matching facilitated by the permissive dd transition in bimetallic single-atom systems. This enabled the reconstruction of the electrochemical reduction process at the atomic level.

Additionally, density functional theory (DFT) calculations revealed that the Fe-As specific bonding and minimum potential energy determination step corresponds to the linear shift of key intermediate-derived s and p peaks to high-energy orbitals. Dynamic evolution of adaptive matching was reproduced from the perspective of the dynamics, the convergence trend of the thermodynamic model, and the annealing simulations, respectively.

This research not only helped optimize catalyst performance, but also confirmed the catalyst's structure-performance relationship through experimental verification.

The combined approach of in situ characterization and theoretical simulation provides unique insights for the investigation of transient reaction dynamic mechanisms and future selective design/screening of nextgeneration catalysts, according to the team.

In-situ XAFS technology combined with DFT computational simulation to explore the microscopic dynamic evolution of electrochemical reactions. (Image by SONG Zongyin)