The BiVO₄ photoanode with 2.4 eV band gap and a-Si photocathode with 1.7 eV band gap are ideal to form a self-driven tandem photoelectrochemical (PEC) water-splitting cell. The main obstacles for such tandem cells are the relatively low activity and stability of BiVO₄ photoanode. Herein, we demonstrate a highly active undoped BiVO₄ cocatalyzed with ultrasmall cobalt borate (CoB_i) via photoassisted electrodeposition. The conformal TiO₂ layer deposited on BiVO₄ surface helps the formation of ultrasmall CoB_i cocatalysts with excellent charge-transfer properties. The resulting BiVO₄ photoanode exhibited a remarkably stable photocurrent of ∼2.5 mA/cm² at 1.23 V vs RHE. By combining the highly active and stable BiVO₄ photoanode with a-Si photocathode, a solar-driven tandem water-splitting cell is successfully fabricated with up to 3% solar-to-hydrogen (STH) conversion efficiency, a fairly high efficiency yet reported for undoped BiVO₄ photoanode.

中文翻译：

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基于纳米多孔BiVO的串联分解水细胞₄光阳极助催化由超小型硼酸钴具有共形的TiO夹着₂层

具有2.4 eV带隙的BiVO ₄光电阳极和具有1.7 eV带隙的a-Si光电阴极是形成自驱动串联光电化学（PEC）水分解池的理想选择。这种串联电池的主要障碍是BiVO ₄光电阳极的相对较低的活性和稳定性。在本文中，我们展示了通过光辅助电沉积与超小硼酸钴（CoB _i）共催化的高活性未掺杂BiVO ₄。沉积在BiVO ₄表面的共形TiO ₂层有助于形成具有优异电荷转移性能的超小型CoB _i助催化剂。生成的BiVO ₄与RHE相比，在1.23 V时，光电阳极显示出约2.5 mA / cm ²的非常稳定的光电流。通过将高活性和稳定的BiVO ₄光电阳极与a-Si光电阴极相结合，成功制造了太阳能驱动的串联水分解池，其太阳能-氢（STH）转换效率高达3％，但据报道效率相当高用于未掺杂的BiVO ₄光电阳极。