Bismuth vanadate (BiVO4) has been widely regarded as a promising photoanode material for photoelectrochemical (PEC) water splitting because of its low cost, its high stability against photocorrosion, and its relatively narrow band gap of 2.4 eV. However, the achieved performance of the BiVO4 photoanode remains unsatisfactory to date because its short carrier diffusion length restricts the total thickness of the BiVO4 film required for sufficient light absorption. We addressed the issue by deposition of nanoporous Mo-doped BiVO4 (Mo:BiVO4) on an engineered cone-shaped nanostructure, in which the Mo:BiVO4 layer with a larger effective thickness maintains highly efficient charge separation and high light absorption capability, which can be further enhanced by multiple light scattering in the nanocone structure. As a result, the nanocone/Mo:BiVO4/Fe(Ni)OOH photoanode exhibits a high water-splitting photocurrent of 5.82 ± 0.36 mA cm-2 at 1.23 V versus the reversible hydrogen electrode under 1-sun illumination. We also demonstrate that the PEC cell in tandem with a single perovskite solar cell exhibits unassisted water splitting with a solar-to-hydrogen conversion efficiency of up to 6.2%.
Science Advances 17 Jun 2016:
Vol. 2, no. 6, e1501764
DOI: 10.1126/sciadv.1501764
http://advances.sciencemag.org/content/2/6/e1501764
钒酸铋因具有低成本，可以针对光腐蚀的高稳定性，以及具有 2.4eV 这样相对较小的带隙，使其被广泛地认为是用于光电化学水分解的一种很有前途的光电阳极材料。然而，目前钒酸铋光电阳极实现的性能仍然不能令人满意，原因是它的载流子扩散距离较短限制了钒酸铋膜吸收足够光所需的总厚度。文中提出的方法是将掺钼的钒酸铋（Mo:BiVO4）沉积在设计好的锥形纳米结构上，这样其中的 Mo:BiVO4层具有较大的有效厚度来保持高度有效的电荷分离能力和光吸收能力，从而可以进一步提高纳米锥结构的多重光散射。最终结果，Mo:BiVO4/Fe(Ni)OOH 纳米锥形光电阳极与可逆氢电极在一个单位的太阳光照下表现出 1.23V 下 5.82±0.36 mA cm-2的高水分解光电流。文中还表明，光电化学电池与一个单一钙钛矿太阳能电池串联在一起时，表现为无辅助水分结，对应的太阳能-氢转化效率提升至 6.2% 。（Science Advances DOI : 10.1126 / sciadv.1501764 ） (新材料在线）
