The utilization of solar energy into photoelectrochemical (PEC) water splitting is a popular approach to store the sustainable energy and minimize the dependence of fossil fuels. Herein, multi-layer BiVO₄ films were synthesized by multi-cycle electrodeposition following by annealing at high temperature. Multi-layer BiVO₄ films have monoclinic scheelite structure, and the morphology is changed from densely compact film to sponge-like network, and then bulk structure with the increase of electro-deposited layers. X-ray photoelectron spectra indicate the presence of abundant oxygen vacancies and V⁴⁺ species in multi-layer BiVO₄, especially for 3-layer one. For visible-light PEC performance, 3-layer BiVO₄ shows the highest photocurrent among the samples, i.e. up to 5.80 mA/cm² in sulfite oxidation and 1.79 mA/cm² in water splitting at 1.23 V versus a reverse hydrogen electrode (RHE) under 1 sun irradiation (100 mW/cm²), with very high IPCE achieved nearly 83% and 25% (at 420 nm), respectively. The extremely high PEC performance of 3-layer BiVO₄ is attributed to its morphology of sponge-like network and the modulated band structure by the oxygen vacancies and V⁴⁺ species. Moreover, the multi-layer BiVO₄ also shows very high photostability. This work provides a multi-layer-construction method for highly visible-light-active PEC anodes for practical applications.

中文翻译：

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具有氧空位和V ⁴⁺物种的多层单斜BiVO ₄，用于高效可见光光电化学应用

将太阳能用于光电化学（PEC）水分解是一种流行的方法，可以存储可持续能源并最大程度地减少对化石燃料的依赖。在此，通过在高温下退火之后的多循环电沉积来合成多层BiVO ₄膜。多层BiVO ₄薄膜具有单斜白钨矿结构，其形貌由致密的薄膜变为海绵状网络，然后随着电沉积层的增加而形成整体结构。X射线光电子能谱表明在多层BiVO _4中存在大量的氧空位和V ⁴⁺物种，特别是对于三层BiVO ₄。为了实现可见光PEC性能，三层BiVO ₄显示出样品中最高的光电流，即在1个太阳辐射（100 mW / cm ²）下，与反向氢电极（RHE）相比，在亚硫酸盐氧化中高达5.80 mA / cm ²，在1.23 V下的水分解中高达1.79 mA / cm ² IPCE很高时，在420 nm时分别达到了近83％和25％。3层BiVO ₄具有极高的PEC性能，这归因于其海绵状网络的形态以及氧空位和V ⁴⁺物种对带结构的调节。此外，多层BiVO ₄     还显示出很高的光稳定性。这项工作为实际应用中的高可见光活性PEC阳极提供了一种多层构造方法。