Carbon-quantum-dots-involved Fe/Co/Ni phosphide open nanotubes for high effective seawater electrocatalytic decomposition

The hollow materials with open structure can accelerate the mass transfer and bubble release rate, which have attracted tremendous attention for electrocatalytic water splitting. In this work, a unique tri-metal phosphide open nanotube structure [FeCoNiP@carbon quantum dots, FCNP@CQDs] is firstly fabricated by a selected etching and phosphating process with a MIL-88A@CQDs (MIL stands for Material of Institute Lavoisier) as the precursor. Benefiting from their open structure, FCNP@CQDs exhibit excellent catalytic performance. In alkaline seawater solution, a low overpotential of 268 mV is required to reach 20 mA cm−2 current density for oxygen evolution reaction, while the η20 of hydrogen evolution reaction is 150 mV. The FCNP@CQDs//FCNP@CQDs electrolyzer requires a voltage of 1.61 V to reach 10 mA cm−2. The integrated strategy of CQDs-doping and construction of hollow open structures may open a new and relatively unexplored path for fabricating high-performance seawater splitting catalysis. [Display omitted] •The open hollow FCN-LDHs@CQDs nanotube is firstly prepared via MOF etching process.•Open hollow structure can accelerate the mass transfer and bubble release.•The involved CQDs and defects can optimize the intrinsic activity of active species.•XPS and in-situ Raman confirm the phase evolution process of anode electrode.