title: Efficient solar-driven water splitting by nanocone BiVO4-perovskite tandem cells.
abstract: 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%.
authors.affiliation: Department of Physics, Tsinghua University, Beijing 100084, China.; Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA.
authors.forename: Yongcai
authors.initials: Y
authors.lastname: Qiu
authors.affiliation: Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.affiliation: Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.affiliation: Michael Grätzel Centre for Mesoscopic Solar Cells, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.affiliation: Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA.
authors.forename: Guangmin
authors.initials: G
authors.lastname: Zhou
authors.affiliation: Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA.
authors.forename: Po-Chun
authors.initials: PC
authors.lastname: Hsu
authors.affiliation: Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA.
authors.forename: Rufan
authors.initials: R
authors.lastname: Zhang
authors.affiliation: Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Liang
authors.affiliation: Department of Physics, Tsinghua University, Beijing 100084, China.
authors.forename: Shoushan
authors.identifier: 0000-0002-8849-7896
authors.initials: S
authors.lastname: Fan
authors.affiliation: Department of Physics, Tsinghua University, Beijing 100084, China.; Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, Jiangsu 215123, China.
authors.forename: Yuegang
authors.identifier: 0000-0003-0344-8399
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA.; SLAC National Accelerator Laboratory, Stanford Institute for Materials and Energy Sciences, 2575 Sand Hill Road, Menlo Park, CA 94025, USA.
authors.forename: Yi
authors.initials: Y
authors.lastname: Cui
mesh_terms: D001729:Bismuth / Q000737:chemistry*; D017610:Calcium Compounds / Q000737:chemistry*; D004566:Electrodes; D053758:Nanoparticles / Q000737:chemistry; D058608:Nanopores; D010087:Oxides / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry; D012993:Solar Energy; D014025:Titanium / Q000737:chemistry*; D014638:Vanadates / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D017610:Calcium Compounds; D010087:Oxides; D014867:Water; C059910:perovskite; C091754:bismuth vanadium tetraoxide; D014638:Vanadates; D012822:Silicon Dioxide; D014025:Titanium; D001729:Bismuth
keywords: Porous BiVO4; light trapping; nanocone array; perovskite solar cell; photoelectrochemical water splitting