Hierarchical Polyoxometallate Confined in Woven Thin Films for Single-Cluster Catalysis: Simplified Electrodes for Far-Fetched O2 Evolution from Seawater

The highly anticipated artificial conversion of water to oxygen for the imperishable growth of renewable energy requires efficient water oxidation catalysts (WOCs) to drive the exciting 4e– transformation at low driving potentials. Herein, we describe the freestanding thin film of P5Q7 (TFPQ), where Preyssler [P5W30O110]14– (P5) clusters are woven with [CH3(CH2)6]4N(Br) chains (Q7) to confine P5 clusters and maximize its catalytic exposure. The TFPQ-supported electrode shows OER at record-low overpotentials at 10 mAcm2 (η10 = 130 and 490 mV), rapid migration of electrons (Tafel, 35 and 56 mVdec–1), turnover frequency (TOF, 8.55 s–1), in alkaline water (1 M KOH), and natural seawater, respectively. Evenly dispersed and confined conducting P5 clusters with a delocalized charge cloud shows ∼3 times lower η10 and eventually high OER efficiency than nonconfined clusters. The TFPQ electrodes showed a prolonged stability of minimum 1000 cycles in alkaline water and seawater, without the leaching of true catalytic species P5.