The
design of cost-effective and efficient electrocatalysts for both hydrogen
evolution reaction (HER) and oxygen evolution reaction (OER) is pivotal
for the molecular hydrogen (H2) production from electrochemical
water splitting as a future energy source. Herein, we show that the
hybridization between multiple HER- and OER-active components is effective
for the design and realization of bifunctional electrocatalysts for
universal water splitting, i.e., in both acidic and
alkaline media. Our strategy relies on the production and characterization
of MoSe2 holey flake:Mo2C ball hybrids supported
by single-walled carbon nanotube (SWCNT) electrocatalysts. Flakes
of MoSe2 are produced through hydrogen peroxide (H2O2)-aided liquid phase exfoliation (LPE), which
promotes both the exfoliation of the materials and the formation of
nanopores in the flakes via chemical etching. The
amount of H2O2 in the solvent used for the exfoliation
process is optimized to obtain ideal high ratio between edge and basal
sites ratio, i.e., high-number of electrocatalytic
sites. The hybridization of MoSe2 flakes with commercial
ball-like shaped Mo2C crystals facilitates the Volmer reaction,
which works in both acidic and alkaline media. In addition, the electrochemical
coupling between SWCNTs (as support) and MoSe2:Mo2C hybrids synergistically enhances both HER- and OER-activity of
the native components, reaching high η10 in acidic
and alkaline media (0.049 and 0.089 V for HER in 0.5 M H2SO4 and 1 M KOH, respectively; 0.197 and 0.241 V for OER
in 0.5 M H2SO4 and 1 M KOH, respectively). The
exploitation of the synergistic effects occurring between multicomponent
electrocatalysts, coupled with the production of the electrocatalysts
themselves through scalable and cost-effective solution-processed
manufacturing techniques, is promising to scale-up the production
of H2
via efficient water splitting for
the future energy portfolio.