Comparative Study on the Photoelectrochemical Hydrogen\nProduction from the Layout Optimization in a Unit Cell

Solar-driven\nwater splitting is achieved by connecting photovoltaics\nwith electrolysis. Recently, integrated approaches of the two configurations\nfor photoelectrochemical reactions have shown great potential in a\ncombined unit, but strategies to address further material and cell\ndevelopment face significant scientific challenges. Here we present\nan experimental demonstration of photoelectrochemical (PEC) unit-cells\nwith efficient separate dual compartments for oxygen evolution and\nhydrogen evolution reactions. The design and fabrication of cell architectures\nwith various degrees of integration are investigated efficient and\nsustainable PEC processes. The effect of the nanostructured silicon\n(Si) photoelectrodes, including the adoption of layer architectures,\nsurface protection layer deposition, and membrane electrode assembly\nis further studied to optimize the design parameters of the PEC unit-cells.\nThis developed PEC cell with the Si photocathode achieved a photocurrent\ndensity of −4.8 mA cm<sup>–2</sup> at −2.0 <i>V</i><sub>cell</sub> and −2.87 mA cm<sup>–2</sup> at −1.6 <i>V</i><sub>cell</sub>. It clearly provides\na critical milestone for unbiased solar water splitting. Practical\nsolar to hydrogen (STH) can be directly estimated in investigating\nPEC performance in this unit-cell as assembled with a solar cell.\nIt is a significantly meaningful step forward in practical solar fuel\nproduction.