Enhancing Visible-Light-Driven Water Splitting with Transition Metal Doping of CeO2 for Improved Photoelectrocatalytic Green Hydrogen Production
Zahra Albu a b, Nawal Al Abass c, Talal Qahtan d, Bandar AlOtaibi b, Mojtaba Abdi-Jalebi a
a Institute for Materials Discovery, University College London, Malet Place, London, WC1E 7JE UK
b The Center of Excellence for Advanced Materials and Manufacturing, King Abdulaziz City for Science and Technology, Riyadh 11442, Saudi Arabia
c Hydrogen Technologies Institute, King Abdulaziz City for Science and Technology, Riyadh 11442, Saudi Arabia
d Physics Department, College of Science and Humanities in Al-Kharj, Prince Sattam Bin Abdulaziz University, Al-Kharj, 11942, Saudi Arabia
Proceedings of The Future of Hydrogen: Science, Applications and Energy Transition (H2Future)
Ibiza, Spain, 2024 April 17th - 19th
Organizers: Carolina Gimbert Suriñach, Sixto Gimenez Julia and Emilio Palomares
Oral, Mojtaba Abdi-Jalebi, presentation 013
Publication date: 27th February 2024

The production of green hydrogen through visible-light-driven water splitting represents an appealing avenue for sustainable and environmentally friendly hydrogen generation[1]. However, the efficiency of photoelectrocatalysis in solar-to-hydrogen conversion is constrained by the limited light absorption of most available semiconductor materials, which typically have wide bandgaps, restricting them to the UV range[2]. Consequently, there is a need to develop catalysts capable of absorbing visible light. In this context, we propose a strategy to enhance the photoelectrocatalytic activity of CeO2 by doping it with transition metals such as Ni and Co. This doping extends the material's visible light absorption and introduces d-states within the forbidden bandgap. Verification of bandgap narrowing and extended visible light absorption was conducted through UV-vis diffuse reflectance, revealing that Ni and Co doping reduced the bandgap of CeO2 from 3.0 eV to 2.7 eV and 2.6 eV, respectively. Density functional theory (DFT) calculations supported these findings, confirming bandgap narrowing and the presence of d-states. Moreover, photoelectrochemical measurements demonstrated superior photoelectrocatalytic activity in the Ni-doped sample compared to Co-doped CeO2. This enhanced catalytic performance is attributed to the introduction of d-states near the Fermi level through Ni doping, while Co doping introduced d-states located near the conduction band of CeO2. Our surface Slab calculations further revealed that Ni-doped CeO2 reduced the Gibbs energy for oxygen evolution reaction (OER) intermediate adsorption compared to pure and Co-doped CeO2. This suggests that doping plays a pivotal role in modulating the electronic environment of the catalyst, facilitating charge transfer through defect d-states near the Fermi level and accelerating reaction kinetics. In summary, our study underscores that doping CeO2 with transition metals like Ni and Co can enhance its photoelectrocatalytic activity for green hydrogen production. Ni doping, in particular, leads to the creation of d-states near the Fermi level, resulting in improved catalytic performance. These findings contribute significantly to the development of efficient catalysts for visible-light-driven water splitting and pave the way for sustainable hydrogen production.

M.A.-J. acknowledge the Department for Energy Security and Net Zero (Project ID: NEXTCCUS), University College London’s Research, Innovation and Global Engagement, and UCL Cities Partnerships Programme Award in Paris for their financial support. M.A.-J. acknowledge the ACT programme (Accelerating CCS Technologies, Horizon2020 Project No. 691712) for the financial support of the NEXTCCUS project (project ID: 327327). M.A.-J. and Z.A. acknowledge Cornell-UCL Global Strategic Collaboration Awards team, UCL-IIT Delhi and UCL- Indian Institute of Science for their financial Support. Z.A. acknowledges King Abdulaziz City for Science and Technology for the PhD Scholarship. The authors thanks King Abdullah University of Science and Technology (KAUST) Supercomputing Laboratory for providing access to supercomputer Shaheen.

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