Bulk and interface engineering with the combined addition of Na⁺ and E⁵⁺ (E = Nb⁵⁺, Ta⁵⁺) in the design of hematite photoanodes

Author(s)

Thomaz, Kelly T. C. ; Rodriguez-Gutierrez, Ingrid ; Souza, Flavio L.

• Document type: Journal article
• Source: Materials Letters; v. 365, p. 5-pg., 2024-04-16.

Abstract

In this letter, the synergistic effects of multiple element modification through a single polymeric precursor solution in hematite-based photoanodes using Na/Nb and Na/Ta as dopants are evaluated. Linear sweep voltammetry curves showed that the photoelectrochemical response was improved after Na/Nb (or Ta) addition. In both circumstances, an anodic shift (similar to 200 mV) in the onset potential was noticeable due to surface states created after Nb5+/Ta5+ segregation. The energetic loss caused by Nb (and Ta) segregation was partially restituted by NiFeOx addition due to the passivation of surface states, acting as recombination centers created by pentavalent modifiers. These combined modifications brought a three and four-fold increase for Na(0.1)HemNb(1.5) NiFeOx and Na(0.1)HemTa(1.0)NiFeO(x) respectively. Charge carrier dynamics analysis studied by intensity modulated photocurrent spectroscopy revealed that the PEC enhancement in both systems is mainly associated with improved charge separation efficiency. (AU)

• FAPESP's process: 17/11986-5 - Generation and storage of New Energy: bringing technological development for the country
• Grantee: Ana Flávia Nogueira
• Support Opportunities: Research Grants - Research Centers in Engineering Program
• FAPESP's process: 17/02317-2 - Interfaces in materials: electronic, magnetic, structural and transport properties
• Grantee: Adalberto Fazzio
• Support Opportunities: Research Projects - Thematic Grants