3 years ago

Activation of a Nickel-Based Oxygen Evolution Reaction Catalyst on a Hematite Photoanode via Incorporation of Cerium for Photoelectrochemical Water Oxidation

Activation of a Nickel-Based Oxygen Evolution Reaction Catalyst on a Hematite Photoanode via Incorporation of Cerium for Photoelectrochemical Water Oxidation
Bryan R. Wygant, Amritesh Rai, Edward J. Evans, Jae Young Kim, Hyungseob Lim, C. Buddie Mullins, Jun-Hyuk Kim
There has been debate on whether Ni(OH)2 is truly catalytically active for the photo/electrocatalytic oxygen evolution reaction. In this report, we synthesized a Ni(OH)2 cocatalyst on a hematite photoanode and showed that, as has been proposed in other studies, the current density varies as a function of scan rate, which arises due to a photoinduced capacitive charging effect. We discovered that this photoinduced charging of Ni2+/3+ can be overcome by mixing cerium nitrate into the Ni precursor solution. Under illumination, the NiCeOx cocatalyst on a hematite photoanode exhibited an approximately 200 mV cathodic shift in onset potential and a ∼53% enhancement in photocurrent at 1.23 V vs RHE. Material characterization by electrochemical impedance spectroscopy revealed that the Ni species create a p–n junction across the charge space region, which facilitates collection of the photogenerated holes by the cocatalyst layer, and core level X-ray photoelectron spectroscopy showed that Ce incorporated into the Ni-based cocatalyst layer may possibly induce the oxidation of the Ni species. In addition, we observed a reduction in binding energies of Ni after photoelectrochemical water splitting reactions, which suggests that the lattice oxygen of the NiCeOx is consumed in the catalytic cycle, forming oxygen vacancies. The NiCeOx cocatalyst, however, was incapable of passivating the surface recombination centers of the hematite photoanode, as indicated by the unaltered flat-band potential determined with Mott–Schottky analysis.

Publisher URL: http://dx.doi.org/10.1021/acsami.7b08239

DOI: 10.1021/acsami.7b08239

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.