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Title: Tandem Core–Shell Si–Ta 3N 5 Photoanodes for Photoelectrochemical Water Splitting

Here, nanostructured core–shell Si–Ta 3N 5 photoanodes were designed and synthesized to overcome charge transport limitations of Ta 3N 5 for photoelectrochemical water splitting. The core–shell devices were fabricated by atomic layer deposition of amorphous Ta 2O 5 onto nanostructured Si and subsequent nitridation to crystalline Ta 3N 5. Nanostructuring with a thin shell of Ta 3N 5 results in a 10-fold improvement in photocurrent compared to a planar device of the same thickness. In examining thickness dependence of the Ta 3N 5 shell from 10 to 70 nm, superior photocurrent and absorbed-photon-to-current efficiencies are obtained from the thinner Ta 3N 5 shells, indicating minority carrier diffusion lengths on the order of tens of nanometers. The fabrication of a heterostructure based on a semiconducting, n-type Si core produced a tandem photoanode with a photocurrent onset shifted to lower potentials by 200 mV. CoTiO x and NiO x water oxidation cocatalysts were deposited onto the Si–Ta 3N 5 to yield active photoanodes that with NiO x retained 50–60% of their maximum photocurrent after 24 h chronoamperometry experiments and are thus among the most stable Ta 3N 5 photoanodes reported to date.
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [1] ;  [2]
  1. Stanford Univ., Stanford, CA (United States)
  2. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
Publication Date:
Grant/Contract Number:
AC02-76SF00515; CHE-1305124; 680-50-1309
Type:
Accepted Manuscript
Journal Name:
Nano Letters
Additional Journal Information:
Journal Volume: 16; Journal Issue: 12; Journal ID: ISSN 1530-6984
Publisher:
American Chemical Society
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; charge transport; Heterojunction; heterostructure; oxygen evolution reaction; photoanode; photoelectrochemical water oxidation
OSTI Identifier:
1360211