Journal article Open Access
Schwarz, Dana; Acharjya, Amitava; Ichangi, Arun; Kochergin, Yaroslav; Lyu, Pengbo; Opanasenko, Maksym V.; Tarábek, Jan; Vacek Chocholoušová, Jana; Vacek, Jaroslav; Schmidt, Johannes; Nachtigall, Petr; Thomas, Arne; Bojdys, Michael J.
Crystalline and amorphous organic materials are an
emergent class of heterogeneous photocatalysts for the generation of
hydrogen from water, but a direct correlation between their structures
and the resulting properties has not been achieved so far. To make a
meaningful comparison between structurally different, yet chemically
similar porous polymers, we present two porous polymorphs of a
triazine-based graphdiyene (TzG) framework from a simple, one-pot
reaction using Cu(I) for TzGCu and Pd(II)/Cu(I) for TzGPd/Cu catalyzed
homocoupling polymerization. The polymers form via irreversible
coupling reactions and give rise to a crystalline (TzGCu) and an
amorphous (TzGPd/Cu) polymorph. Notably, the crystalline and
amorphous polymorphs are narrow-gap semiconductors with
permanent surface areas of 660 m2 g-1 and 392 m2 g-1, respectively.
Hence, both polymers are ideal heterogeneous photocatalysts for
water splitting with some of the highest hydrogen evolution rates
reported thus far up to 972 μmol h-1 g-1 with and 276 μmol h-1 g-1
without Pt co-catalyst. We conclude, that crystalline order improves
delocalisation, while the amorphous polymorph requires a co-catalyst
for efficient charge transfer; this will need to be considered in future
rational design of polymer catalysts and organic electronics.