Fig. 5: Catalyst’s applications in HSE.

a Schematic illustration of hydrogen production by renewables-powered HSE with costless seawater and industrial sulfion-containing sewage as the feeds. b The digital image of a TEG-driven HSE. c The current density or voltage versus time curves of this TEG-driven HSE in 1 M NaOH seawater. d The digital image of a solar cell driven HSE. e The current density or voltage versus time curves of this solar cell driven HSE in 1 M NaOH seawater.