TY - JOUR

T1 - Nitrogen/Carbon-Coated Zero-Valent Copper as Highly Efficient Co-catalysts for TiO2 Applied in Photocatalytic and Photoelectrocatalytic Hydrogen Production

AU - Ombaka, Lucy M.

AU - Curti, Mariano

AU - McGettrick, James D.

AU - Davies, Matthew L.

AU - Bahnemann, Detlef W.

N1 - Funding information: This work was funded by the Alexander von Humboldt Foundation. Special thanks go to Felix Best for sample calcination and Patrick Bessel for the UV–vis analysis. We thank Prof. Armin Feldhoff and Frank Steinbach for conducting the TEM analysis. M.C. is grateful to the Deutscher Akademischer Austauschdienst (DAAD) together with the Ministerio de Educación, Cultura, Cienciay Tecnología (Argentina) for his ALEARG scholarship. J.D.M. and M.L.D. are grateful for the support of the EPSRC, Welsh Government (Project 80708) and Innovate UK for the SPECIFIC Innovation and Knowledge Centre (EP/N020863/1). M.L.D. is grateful for the financial support of the EPSRC (EP/R016666/1 and EP/S001336/1).

PY - 2020/7/8

Y1 - 2020/7/8

N2 - 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.

AB - 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.

KW - carbon-coated copper

KW - nanoparticles

KW - photocatalytic hydrogen production

KW - photoelectrochemical hydrogen evolution

KW - solvothermal synthesis

KW - titanium dioxide

UR - http://www.scopus.com/inward/record.url?scp=85088210983&partnerID=8YFLogxK

U2 - 10.1021/acsami.0c06880

DO - 10.1021/acsami.0c06880

M3 - Article

C2 - 32525294

VL - 12

SP - 30365

EP - 30380

JO - ACS Applied Materials & Interfaces

JF - ACS Applied Materials & Interfaces

SN - 1944-8244

IS - 27

ER -