High-resolution X-ray diffraction experiments, theoretical calculations and atom-specific X-ray absorption experiments were used to investigate two nickel complexes, (MePh 3 P) 2 [Ni II (bdtCl 2 ) 2 ]·2(CH 3 ) 2 SO [complex (1)] and (MePh 3 P)[Ni III (bdtCl 2 ) 2 ] [complex (2)]. Combining the techniques of nickel K - and sulfur K -edge X-ray absorption spectroscopy with high-resolution X-ray charge density modeling, together with theoretical calculations, the actual oxidation states of the central Ni atoms in these two complexes are investigated. Ni ions in two complexes are clearly in different oxidation states: the Ni ion of complex (1) is formally Ni II ; that of complex (2) should be formally Ni III , yet it is best described as a combination of Ni 2+ and Ni 3+ , due to the involvement of the non-innocent ligand in the Ni— L bond. A detailed description of Ni—S bond character (σ,π) is presented.
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This content will become publicly available on May 10, 2024
Nature-Inspired Design of Nano-Architecture-Aligned Ni 5 P 4 -Ni 2 P/NiS Arrays for Enhanced Electrocatalytic Activity of Hydrogen Evolution Reaction (HER)
- Award ID(s):
- 1827745
- NSF-PAR ID:
- 10420068
- Date Published:
- Journal Name:
- ACS Applied Materials & Interfaces
- Volume:
- 15
- Issue:
- 18
- ISSN:
- 1944-8244
- Page Range / eLocation ID:
- 22036 to 22050
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Self‐sustaining photocatalytic NO3−reduction systems could become ideal NO3−removal methods. Developing an efficient, highly active photocatalyst is the key to the photocatalytic reduction of NO3−. In this work, we present the synthesis of Ni2P‐modified Ta3N5(Ni2P/Ta3N5), TaON (Ni2P/TaON), and TiO2(Ni2P/TiO2). Starting with a 2 mM (28 g/mL NO3−−N) aqueous solution of NO3−, as made Ni2P/Ta3N5and Ni2P/TaON display as high as 79% and 61% NO3−conversion under 419 nm light within 12 h, which correspond to reaction rates per gram of 196 μmol g−1 h−1and 153 μmol g−1 h−1, respectively, and apparent quantum yields of 3–4%. Compared to 24% NO3−conversion in Ni2P/TiO2, Ni2P/Ta3N5and Ni2P/TaON exhibit higher activities due to the visible light active semiconductor (SC) substrates Ta3N5and TaON. We also discuss two possible electron migration pathways in Ni2P/semiconductor heterostructures. Our experimental results suggest one dominant electron migration pathway in these materials, namely: Photo‐generated electrons migrate from the semiconductor to co‐catalyst Ni2P, and upshift its Fermi level. The higher Fermi level provides greater driving force and allows NO3−reduction to occur on the Ni2P surface.
