The future of water-derived hydrogen as the “sustainable
energy source” straightaway bets on the success of the sluggish
oxygen-generating half-reaction. The endeavor to emulate the natural
photosystem II for efficient water oxidation has been extended across
the spectrum of organic and inorganic combinations. However, the achievement
has so far been restricted to homogeneous catalysts rather than their
pristine heterogeneous forms. The poor structural understanding and
control over the mechanistic pathway often impede the overall development.
Herein, we have synthesized a highly crystalline covalent organic
framework (COF) for chemical and photochemical water oxidation. The
interpenetrated structure assures the catalyst stability, as the catalyst’s
performance remains unaltered after several cycles. This COF exhibits
the highest ever accomplished catalytic activity for such an organometallic
crystalline solid-state material where the rate of oxygen evolution
is as high as ∼26,000 μmol L–1 s–1 (second-order rate constant k ≈
1650 μmol L s–1 g–2). The
catalyst also proves its exceptional activity (k ≈
1600 μmol L s–1 g–2) during
light-driven water oxidation under very dilute conditions. The cooperative
interaction between metal centers in the crystalline network offers
20–30-fold superior activity during chemical as well as photocatalytic
water oxidation as compared to its amorphous polymeric counterpart