Multilayer Strategy for Photoelectrochemical Hydrogen Generation: New Electrode Architecture that Alleviates Multiple Bottlenecks

Years of research have demonstrated that the use of multiple components is essential to the development of a commercial photoelectrode to address specific bottlenecks, such as low charge separation and injection efficiency, low carrier diffusion length and lifetime, and poor durability. A facile strategy for the synthesis of multilayered photoanodes from atomic-layer-deposited ultrathin films has enabled a new type of electrode architecture with a total multilayer thickness of 15–17 nm. We illustrate the advantages of this electrode architecture by using nanolayers to address different bottlenecks, thus producing a multilayer photoelectrode with improved interface kinetics and shorter electron transport path, as determined by interface analyses. The photocurrent density was twice that of the bare structure and reached a maximum of 33.3 ± 2.1 mA cm −2 at 1.23 V RHE . An integrated overall water-splitting cell consisting of an electrocatalytic NiS cathode and Bi 2 S 3 /NiS/NiFeO/TiO 2 photoanode was used for precious-metal-free seawater splitting at a cell voltage of 1.23 V without degradation. The results and root analyses suggest that the distinctive advantages of the electrode architecture, which are superior to those of bulk bottom-up core–shell and hierarchical architectures, originate from the high density of active sites and nanometer-scale layer thickness, which enhance the suitability for interface-oriented energy conversion processes.