An Operando X-ray Absorption Spectroscopy Study of a NiCu-TiO2 Photocatalyst for H-2 Evolution

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61989592%3A15310%2F20%3A73604394" target="_blank" >RIV/61989592:15310/20:73604394 - isvavai.cz</a>

Result on the web

<a href="https://pubs.acs.org/doi/full/10.1021/acscatal.0c01373" target="_blank" >https://pubs.acs.org/doi/full/10.1021/acscatal.0c01373</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1021/acscatal.0c01373" target="_blank" >10.1021/acscatal.0c01373</a>

Result language

angličtina

Original language name

An Operando X-ray Absorption Spectroscopy Study of a NiCu-TiO2 Photocatalyst for H-2 Evolution

Original language description

Cu- or Ni-decorated semiconductors represent a potential low-cost alternative to noble-metal-modified photocatalysts. Even more effective are bimetallic NiCu nanoparticles, which can provide a remarkable photocatalytic H-2 evolution enhancement compared to single-element Cu or Ni systems. The main concern of such alloyed co-catalysts is their activity with respect to alteration of their elemental composition and oxidation state over reaction time. Ex situ characterization techniques provide controversial interpretations of the co-catalytic role of the individual elements. Hypotheses such as the in situ reduction of &quot;native&quot; Ni or Cu species during photocatalysis, the oxidation of metallic Cu or Ni into oxides or hydroxides, or the formation of p-n junctions or core/shell structures have been proposed. Herein, we present an operando X-ray absorption spectroscopy study of a NiCu-TiO2 system under UV light illumination in ethanol-water solutions, i.e., under photocatalytic H-2 evolution conditions. The experimental approach allows for monitoring in real time chemical changes that take place in the co-catalyst under intermittent illumination, i.e., under light on-off cycles. We show that while Ni and Cu are partially oxidized in the as-formed NiCu co-catalyst (air-formed surface oxides or hydroxides) and undergo partial dissolution in the liquid phase under dark conditions, such Ni and Cu oxidized and dissolved species are reduced/redeposited as a bimetallic NiCu phase at the TiO2 surface under illumination. The dissolution/redeposition mechanism is triggered by TiO2 conduction band electrons. We not only prove a UV-light-induced healing of the NiCu co-catalyst but also unambiguously demonstrate that the species responsible for the strongly enhanced photocatalytic H-2 evolution of NiCu nanoparticles are the metallic states of Ni and Cu.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

10403 - Physical chemistry

Project

—

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2020

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

ACS Catalysis

ISSN

2155-5435

e-ISSN

—

Volume of the periodical

10

Issue of the periodical within the volume

15

Country of publishing house

US - UNITED STATES

Number of pages

10

Pages from-to

8293-8302

UT code for WoS article

000562075000027

EID of the result in the Scopus database

2-s2.0-85090974452