Nitrogen/Carbon-Coated Zero-Valent Copper as Highly Efficient Co-catalysts for TiO₂ Applied in Photocatalytic and Photoelectrocatalytic Hydrogen Production

authored by

Lucy M. Ombaka, Mariano Curti, James D. McGettrick, Matthew L. Davies, Detlef W. Bahnemann

Abstract

Zero-valent copper (Cu0) is a promising co-catalyst in semiconductor-based photocatalysis as it is inexpensive and exhibits electronic properties similar to those of Ag and Au. However, its practical application in photocatalytic hydrogen production is limited by its susceptibility to oxidation, forming less active Cu species. Herein, we have carried out in situ encapsulation of Cu0 nanoparticles with N-graphitic carbon layers (14.4% N) to stabilize Cu0 nanoparticles (N/C-coated Cu) and improve the electronic communication with a TiO2 photocatalyst. A facile solvothermal procedure is used to coat the Cu0 nanoparticles at 200 °C, while graphitization is achieved by calcination at 550 °C under an inert atmosphere. The resultant N/C-coated Cu/TiO2 composites outperform the uncoated Cu counterparts, exhibiting a 27-fold enhancement of the hydrogen evolution rate compared to TiO2 and achieving a rate of 19.03 mmol g-1 h-1 under UV-vis irradiation. Likewise, the N/C-coated Cu co-catalyst exhibits a less negative onset potential of-0.05 V toward hydrogen evolution compared to uncoated Cu (ca.-0.30 V). This superior activity is attributed to coating Cu0 with N/C, which enhances the stability, electronic communication with TiO2, conductivity, and interfacial charge transfer processes. The reported synthetic approach is simple and scalable, yielding an efficient and affordable Cu0 co-catalyst for TiO2.

Organisation(s)

Institute of Technical Chemistry
Laboratory of Nano and Quantum Engineering

External Organisation(s)

Technical University of Kenya (TU-K)
Swansea University
University of KwaZulu-Natal
Saint Petersburg State University

Type

Article

Journal

ACS Applied Materials & Interfaces

Volume

12

Pages

30365-30380

No. of pages

16

ISSN

1944-8244

Publication date

08.07.2020

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

General Materials Science

Sustainable Development Goals

SDG 7 - Affordable and Clean Energy

Electronic version(s)

https://doi.org/10.1021/acsami.0c06880 (Access: Closed)