Electroactive bacteria produce well-defined nanosized metal catalysts with remarkable water-splitting performance.
A biological method to generate metal nanoclusters using the electroactive bacterium Geobacter sulfur reduction offers an inexpensive and sustainable solution for the synthesis of high performance catalysts for various applications such as water splitting. There is a possibility.
Metal nanoclusters contain less than 100 atoms and are much smaller than nanoparticles. Although they have unique electronic properties, they also possess numerous active sites on their surface that are available for catalysis. There are several methods for synthesizing metal nanoclusters, but most require multiple steps involving toxic substances and harsh temperature and pressure conditions.
Biological methods are expected to provide an environmentally friendly alternative to conventional chemical synthesis. However, so far only large nanoparticles with a wide range of sizes have been obtained. “We found a way to control the size of the nanoclusters,” says Ph.D. Rodrigo Jimenez-Sandoval. KAUST’s he is a candidate for Pascal Saikaly’s group.
Having previously shown that the surface of electroactive bacterial cells can serve as a support for single metal atoms, Cycare’s team investigated the creation of biohybrid materials. These consisted of palladium nanoclusters immobilized on the bacterial surface of G. sulfurreducens cells. This bacterium is readily found in soil, can transfer electrons to extracellular metals, and can also conduct electricity when grown on the electrodes of microbial electrochemical systems. In this project, it served as a reducing agent and conducting scaffold for nanoclusters.
Using chemical synthesis of the nanoparticles, the researchers decided to control the metal precursor concentration in the setup, and the effort paid off, says Jimenez-Sandoval. “To come up with this idea, I had to think of G.sulfurreducens as a chemical rather than a biological entity.”
They found that the stepwise addition of metal precursors was the key to fine-tuning the size and distribution of the nanoclusters and, ultimately, the catalytic performance.
As a proof-of-concept, the researchers used as-synthesized nanoclusters anchored to the bacterial surface for the overall water-splitting reaction, which involves electrochemically splitting water into gaseous hydrogen and oxygen. was evaluated for its catalytic performance. The nanoclusters outperformed the reference platinum- and iridium-based catalysts used for hydrogen and oxygen evolution reactions in alkaline solutions.
“These results have very important implications for practical applications, because catalysts synthesized by biological methods are not only cheap and simple, but also environmentally friendly,” says Jimenez-Sandoval. says Mr.
The team is now working on producing bio-hybrid catalysts that are less precious metal dependent and use more abundant and cheaper materials to make the strategy more sustainable.
Original: Bacterial pathways to cleaner catalysis
Than: King Abdullah University of Science and Technology
