RT Journal Article
T1 Interfacial charge carrier dynamics of Bi2Fe4O9 photoanodes: interplay between charge transfer and recombination
A1 Expósito Gálvez, Juan Carlos
A1 Francisco J. Peón-Díaz, 
A1 Deimer R. Gómez-Mejía, 
A1 Omar Jiménez-Sandoval, 
A1 Oskam, Gerko
K1 Internal quantum efficiency
K1 Hole scavenger
K1 Photoelectrochemical water splitting
K1 Intensity-modulated photocurrent spectroscopy
K1 Charge carrier dynamic
K1 Surface recombination
AB The charge carrier dynamics of Bi2Fe4O9 thin-film photoanodes are investigated using electrochemical impedance spectroscopy (EIS) and intensity-modulated photocurrent spectroscopy (IMPS) as a function of applied potential, light intensity, and charge transfer rate, modulated by adding sulfite as a hole-accepting redox species. The photocurrent strongly depends on sulfite concentration, reflecting a transition from surface recombination limited to charge transfer dominated behavior. EIS indicates that the effective interfacial capacitance includes semiconductor contributions and is comparable in magnitude to the Helmholtz capacitance. IMPS reveals a second characteristic time constant under suppressed recombination at more positive applied potentials and higher sulfite concentration. Numerical IMPS simulations reproduce the evolution from a pronounced 1st quadrant contribution to two distinct loops in the 4th quadrant, showing that the second loop can emerge when charge transfer prevails over recombination and the semiconductor and Helmholtz capacitance values are similar. These results establish a framework for interpreting multiple time constant behavior in photoelectrochemical systems.
PB Elsevier
YR 2026
FD 2026-09-25
LK https://hdl.handle.net/10433/27446
UL https://hdl.handle.net/10433/27446
LA en
NO International Journal of Hydrogen Energy 278 (2026) 157754
NO Proyectos de investigaciónConsejería de Universidad, Investigación e Innovación of the Junta de Andalucía (Spain) under grant ProyExcel_00543 (H2SOLDIR)Ministerio de Ciencia e Innovación of Spain, Agencia Estatal de Investigación (AEI) and EU (FEDER) under grant PID2022-140061OB-I00 (DEEPMATSOLAR)
NO Universidad Pablo de Olavide. Departamento de Sistemas Físicos, Químicos y Naturales
DS RIO
RD Oct 15, 2026