Protein denaturation induced electrocatalytic hydrogen evolution

Abstract In recent years, there has been an increasing interest in designing economically viable metal-free carbon-supported catalysts for hydrogen-based energy technologies. Here we propose carbon nanotubes (CNTs) covalently functionalized with peptides or proteins as effective catalysts for electrochemical hydrogen evolution reaction (HER). We demonstrate that the HER activity of pristine CNTs can be greatly enhanced via simple functionalization by electrically insulating macromolecules. The roles of the conductive residues and the nitrogen content of the proteins, as well as the importance of their covalent connectivity with the CNTs, have been established. Moreover, we have observed a multifold enhancement in the HER current density due to electrochemical protein denaturation induced by the acidic medium used for HER. We have provided mechanistic insights into the HER activity of different metal-free peptides and proteins. Our work opens up new avenues in carbon-based metal-free HER catalysis, where, by careful selection of natural proteins, both the onset potential and the current density of the HER can be augmented.