Shuo Li

The efficient utilization of solar energy in battery systems has emerged as a crucial strategy for promoting green and sustainable development. In this study, an innovative dual‐photoelectrode vanadium–iron energy storage battery (Titanium dioxide (TiO₂) or Bismuth vanadate (BiVO₄) as photoanodes, polythiophene (pTTh) as photocathode, and VO²⁺/Fe³⁺ as redox couples.) is proposed, which can autonomously charge under sunlight. The dual‐photoelectrode structure enables the efficient harnessing of solar energy. All processes are spontaneous and do not require external power sources. It is noteworthy that the vanadium–iron energy storage battery demonstrates excellent stability and remarkably low cost. The results show that the combinations of TiO₂‐pTTh and BiVO₄‐pTTh as photoelectrodes achieve spontaneous conversion rates of 29.17% and 25.46% for VO²⁺ and 25.6% and 23% for Fe³⁺ after 4 h of light charging. This study offers a promising solution for the development of large‐scale, low‐cost solar energy storage batteries.

A CoOOH cocatalyst overlayer is electrochemically deposited on the BiVO4 surface, and thermal annealing converted CoOOH to Co3O4 in situ. The core difference between the two cocatalysts is whether they are permeable to the electrolyte, which leads to their thermodynamic difference in enhancing the photoelectrochemistry water oxidation performance. We demonstrate experimentally that CoOOH can only passivate surface states apparently, whereas Co3O4 can passivate surface states chemically. Most importantly, CoOOH shows "bulk" redox behavior consistent with electrolyte permeability, which can accumulate holes and generate a larger photovoltage.