Donor-Acceptor Nanocarbon Ensembles to Boost Metal-Free All-pH Hydrogen Evolution Catalysis by Combined Surface and Dual Electronic Modulation

A combined surface and dual electronic modulation strategy is used to realize metal-free all-pH catalysis towards the hydrogen evolution reaction (HER) by coupling a N-doped carbon framework (MHCF, electron acceptors) derived from MOFs with higher-Fermi-level pure carbon nanotubes (CNTs, electron donors), followed by surface modification with carboxyl-group-rich polymers. Although the three constituents are inactive, as-assembled ternary membranes yield superior HER performance with low overpotentials and high durability (<= 5 % activity loss over 100 h) at all pH values. The C adjacent to pyrrolic N in MHCF is the most active site and the induced directional interfacial electron transfer from CNTs to MHCF coupled with N-driven intramolecular electron transfer in MHCF optimizes Gibbs free energy for hydrogen adsorption (Delta G(H*)) near zero, while the polymer modulation enables local H+ enrichment in acidic media and enhanced water adsorption and activation in neutral and basic media.