The setting that is currently most accredited for development based on renewable energy sources is that which goes by the name of hydrogen economy. The solution for achieving this ambitious goal lies in the sustainable production of hydrogen from water using a low-cost electrochemical process. This hydrogen is usually referred to as “green hydrogen”, on account of its low environmental impact and the virtually infinite availability of the raw material should it be possible to use water from the oceans.
However, it calls for an optimisation of the catalysts that are essential to making the electrochemical process affordable and efficient. Researchers in the field are currently studying a rational path that makes it possible to optimise the catalytic materials needed to achieve this goal.
The Surface Science and Catalysis Group (SSCG) of the University of Padua Department of Chemical Sciences (DiSC) directed by Professor Gaetano Granozzi, in conjunction with the Milan-Bicocca University theoretical group directed by Professor Cristiana Di Valentin, has achieved an extraordinary result that will have a great impact on future developments in the hydrogen production field.
The article "Operando visualization of the hydrogen evolution reaction with atomic scale precision at different metal-graphene interfaces" (DOI: 10.1038/s41929-021-00682-2) published in the journal Nature Catalysis, reports on the research led by Stefano Agnoli of the University of Padua Department of Chemical Sciences using an extremely sophisticated instrument (Electrochemical Scanning Tunneling Microscopy, EC-STM) developed in Padua in concert with the electrochemistry group of the same Department, in which the single catalytic sites were observed during the electrochemical process of hydrogen production with atomic resolution (a method usually referred to using the term “in operando”). The EC-STM method was applied to innovative catalytic systems based on two-dimensional materials containing graphene and non-noble metals, which represent an alternative route to the standard materials currently used for the electrochemical decomposition of water requiring the use of noble metals with a high cost and limited availability. The quality of the data obtained is unprecedented and was interpreted by means of state-of-the-art quantum mechanical simulation methods developed at Milan-Bicocca University.
“This study made it possible to identify the presence of catalytic sites with atomic precision and to evaluate their ability to produce hydrogen directly in situ. This truly unique combination of spatial resolution and quantification of electrocatalytic activity,” explains study coordinator Stefano Agnoli, “allows us to establish with extreme accuracy the relationships between the structure of the matter and chemical reactivity and therefore provides the information required to build very high-efficiency catalysts atom by atom.”
"The achievement of these results,” says Gaetano Granozzi, “was made possible by the lengthy experience gained by the University of Padua SSCG, which has worked in the field since it was established in 1990".
"The methods and computational resources currently available,” claims Cristiana Di Valentin, “enable us to simulate systems that are very close to the actual experimental sample with extraordinary benefits for the interpretation of observations in terms of the atomic properties of the matter and reaction mechanisms".