Precious metal Ir-ALD process engineered 2D V-MXene advanced heterostructures for next-generation hydrogen evolution electrocatalyst

Abstract

Precious metals are rare, requiring efficient and intelligent uses from single atoms to nanoclusters compared to their bulk counterparts for clean and green electrocatalysis applications. 2D layered MXene nanomaterials family welcomes structural and compositional variation avenues for their hydrogen evolution reaction (HER) electrolysis activities for sustainable hydrogen energy. To achieve a low over-potential value to cross the electrochemical energy barrier, producing high current density and low Tafel slopes critical performance parameters, we introduce highly efficient atomic layer deposited (ALD) iridium (Ir) on the least explored 2D delaminated VMXene (ALDIr/V-MXene) for suitable use of expensive Ir. By an innovative, rational design of ALDIr/V-MXene heterostructure with controlled Ir-ALD process cycles (50-200), 2D layered V-MXene's accessible electrocatalytic active sites, hence their overall electrochemical energy conversion performance could be monitored and explored as desired. The optimized ALDIr-150/V-MXene electrocatalyst demonstrates the best HER catalytic performance among all designed ALDIr/V-MXene heterostructures, requiring a very low 91 mV overpotential to reach a standard current density (10 mA cm(-2)) and only 204 mV overpotential for its 10-times with fast electron transfer kinetics. The exceptionally high electrocatalytic activities support the precise role of Ir precious single atoms/nanoclusters engineering to the delaminated V-MXene through a well-controlled self-limiting ALD technique as established by first-principles computational methods. Ir single atoms/nanoclusters and their successful formation of advanced ALDIr/V-MXene heterostructure comprehensively probed using next-generation ultrahigh-resolution scanning/transmission electron microscopies via cutting-edge spherical aberration correction technology. To the best of our knowledge, this is the first work on the precise use of Ir precious metals (single atoms/nanoclusters) on 2D V-MXene via ALD for successful HER electrocatalysis applications, paving the way forward for practical application-oriented other 2D nanomaterials and MXene families design through industrially preferred ALD technology.