1 research outputs found
Tailoring Metal-Ion-Doped Carbon Nitrides for Photocatalytic Oxygen Evolution Reaction
Poly(heptazine
imides) (PHIs) have emerged as prominent
layered
carbon nitride-based materials with potential oxygen evolution reaction
(OER) catalytic activity owing to their strong VIS light absorption,
long excited-state lifetimes, high surface-to-volume ratios, and the
possibility of tuning their properties via hosting different metal
ions in their pores. A series of metal-ion-doped PHI-M (M = K+, Rb+, Mg2+, Zn2+, Mn2+, and Co2+) were first systematically explored
using density functional theory calculations. These simulations led
an in-depth understanding of the microscopic OER mechanism in these
systems and identified PHI-Co2+ as the best OER catalyst
of this family of PHIs, whereas PHI-Mn2+ can be an alternative
promising OER catalyst. This level of performance was attributed to
a thermodynamically favorable formation of the reaction intermediates
as well as its red-shifted absorption in the VIS region involving
the population of long-lived states, as revealed by time-dependent
density functional theory calculations. We further demonstrated that
the electronic properties of the *OH intermediates (Bader population,
crystal orbital Hamilton population analysis, and adsorption energies)
are reliable descriptors to anticipate the OER activity of this family
of PHIs. This rational analysis paved the way toward the prediction
of the OER performance of another PHI-M derivative, i.e., PHI-Fe2+. The computationally explored PHI-Fe2+, PHI-Mn2+, and PHI-Co2+ systems were then synthesized alongside
PHI-K+, and their photocatalytic OER activities were assessed.
These experimental findings confirmed the best photocatalytic OER
performance for PHI-Co2+ with an oxygen production of 31.2
μmol·h–1 that is 60 times higher than
the pristine g-C3N4 (0.5 μmol·h–1), whereas PHI-Fe2+ and PHI-Mn2+ are seen as alternative OER catalysts with attractive oxygen production
of 11.20 and 4.69 μmol·h–1, respectively.
Decisively, this joint experimental–computational study reveals
PHI-Co2+ to be among the best of the OER catalysts so far
reported in the literature including some perovskites