Carbon nanopore and anchoring site-assisted general construction of encapsulated metal (Rh, Ru, Ir) nanoclusters for highly efficient hydrogen evolution in pH-universal electrolytes and natural seawater

Abstract

Metal nanocluster-catalyzed hydrogen evolution through water splitting has received substantial interest toward the implementation of hydrogen economy. However, the general and efficient fabrication of well-defined and ligand-free metal nanoclusters (NCs) with precise sizes for efficient hydrogen evolution in various electrolytes remains a formidable challenge. We report herein the synthesis of well-distributed and ligand-free metal (Rh, Ru, Ir) NCs with monodispersity by utilizing nitrogen-doped hollow carbon spheres (NHCSs) as supporting matrices. Due to the spatial confinement of carbon nanopores and the anchoring sites of nitrogen atoms from NHCSs, metal NCs (MNCs) with diameters of sub-2.0 nm (1.97 ± 0.57 nm for Rh NCs, 1.48 ± 0.45 nm for Ru NCs and 1.34 ± 0.69 nm for Ir NCs) are evenly dispersed on NHCSs. Among the catalysts, Rh/NHCSs exhibit not only excellent electrocatalytic activity for the hydrogen evolution reaction (HER) (10 mV in 0.5 M H₂SO₄, 7 mV in 1.0 M PBS and 6 mV in 1.0 M KOH), but also high stability and long-term durability within the whole pH range, outperforming the commercial Pt/C and most of the previously reported catalysts. Meanwhile, this catalyst can be employed for the HER in natural seawater with high activity, stability and long-term durability. This work proposes a simple and effective method to fabricate highly dispersed MNCs with high performance for pH-universal water/seawater splitting.