Re nanoflower-decorated carbon cloth for pH-universal hydrogen evolution reaction: Unveiling the intrinsic electrocatalytic activity of metallic Re

•Electrocatalytic Re nanoflowers (Re NFs) were grown on a carbon cloth (CC) substrate.•Optimal synthesis and growth mechanism of Re NFs on CC were validated.•Density functional theory (DFT) calculations determined intrinsic HER activity of Re.•Hydrogen evolution reaction (HER) activity of Re in different pH environments was evaluated.•ReNF@CC performed eminent HER activities with significantly reduced overpotentials.