NiFe Alloy Protected Silicon Photoanode for Efficient Water Splitting

Abstract

time-saving, ecofriendly, and controllable, avoiding the expensive and complicated ALD process. [22] The resulting np + -Si/ SiO x /NiFe photoanode exhibited an extremely large photovoltage of 620 mV, and a high solar-to-O 2 efficiency of 3.3%, a low onset potential of 0.89 V versus RHE (Reversible Hydrogen Electrode) for OER, and achieved a light-limited photocurrent density of 30.7 mA cm −2 at 1.23 V versus RHE in 1.0 m KOH electrolyte. To the best of our knowledge, the performance of np + -Si/SiO x /NiFe photoanode is much superior to those of the counterparts reported previously. The NiFe OEC/electrolyte interface has also been studied by introducing H 2 O 2 as a hole scavenger, revealing that the hole injection efficiency at NiFe/electrolyte interface is much higher than those at single metal (Fe or Ni)/electrolyte interfaces.The structure of np + -Si/SiO x /NiFe photoanode is schematically illustrated in Figure 1a.

Solar‐to‐Hydrogen Energy Conversion Based on Water Splitting

“…[22,[74][75][76][77][78][79][80] The semiconductor materials are loaded on the electrode surface as a thin film to absorb light for the generation of activated electrons and holes. [81] Nevertheless, cells composed of a photoanode/photocathode and a noble-metal-based counter electrode would be more practical, as shown in Figure 2i,j. Water is oxidized on the anode by the photogenerated holes.…”

Light‐Induced Activation of Adaptive Junction for Efficient Solar‐Driven Oxygen Evolution: In Situ Unraveling the Interfacial Metal–Silicon Junction

“…These Ni 0 atoms could diffuse toward the Si surface, and thus the silicide phase (i.e., NiSi) could be generated following the electroless reduction of Ni cations. [9,18,21] The present results revealed that this photoinduced adaptive layer can significantly increase the band bending near the silicon/metal/electrolyte interface and thereby induce a higher barrier height, thereby leading to the enhancement of photovoltage. Guided by all these findings, we propose that the formation of this adaptive phase concurs with the transformation of nickel metal into nickel oxides/oxyhydroxides and the presence of exposed silicon oxide on the electrolyte/electrode interface, as displayed in the schematic for photoinduced water oxidation on n-Si@Ni (Figure 8a).…”

“…Most importantly, we verified that this adaptive phase was formed at the junction between silicon and nickel with a fringe distance of 0.186 nm, corresponding to the (102) lattice plane of orthorhombic NiSi. 2019, 9,1901308 (a Si = 5.468 Å) matches with two orthorhombic NiSi (200) lattices (a NiSi = 3.060 Å). Energy Mater.…”

“…The observed frequencies and the high intensity ratio of I A /I B can be assigned to that of γ-NiOOH. 2019, 9,1901308 response (19 mA cm −2 ) at a thermodynamic potential requirement for water splitting (1.23 V) in alkaline solution. These results also confirm that the γ-NiOOH and β-NiOOH were sequentially generated at a potential range from 1.0 to 1.35 V versus RHE in the dark condition.…”

“…The mean thickness of the photoinduced NiSi layer is determined to be ≈4.5 ± 0.3 nm as illustrated in Figure S16 (Supporting Information), in which the sample was prepared from n-Si@Ni after photoinduced water oxidation at 1.4 V versus RHE for one hour. 2019, 9,1901308 In situ X-ray absorption spectroscopy measurements of the n-Si@Ni photoanode during the (photo)electrochemical water oxidation reaction: a) Digital photograph of the customized cells used for the in situ X-ray absorption measurements. This observation was also confirmed by X-ray photoelectron spectroscopy (XPS) analysis of the postphotoelectrode ( Figure S18, Supporting Information).…”