Photoactive and Ultrastable Silicon/Boron Doped Diamond Photoanodes Enable Longstanding Photoinduced Electrochemiluminescence
Changlin Zhou, Clément Briquet‐Laugier, Bertrand Goudeau, Sirine Ben Khemis, Zonghua Wang, Emmanuel Scorsone, Gabriel Loget, Neso SojicABSTRACT
The lifetime of narrow bandgap photoanodes, employed in harsh photoelectrochemical energy conversion processes, relies on the protection layers that shield the semiconductor from severe oxidative degradation and passivation caused by the electrolyte. Here, we report ultrastable n ‐Si‐based photoanodes, coated with boron‐doped diamond (BDD) thin films, as an alternative to the transition metal‐coated Si photoelectrodes employed so far for upconversion photoinduced electrochemiluminescence (ECL). Under near‐infrared (λ exc = 850 nm) excitation, the ( n ‐Si/BDD) heterojunction generates a stable 0.4 V photovoltage, driving efficient optical upconversion to visible photoinduced ECL (PECL) emission with both model ECL systems: luminol/H 2 O 2 (pH 13, λ PECL = 450 nm) and [Ru(bpy) 3 ] 2+ /TPrA (pH 7.4, λ PECL = 630 nm), both at remarkably low potentials. Benefiting from the structural integrity and chemical inertness of the BDD surface, the photoanode sustains continuous operation for more than 100 h in the neutral electrolyte with periodic renewal and can be regenerated after fouling in the alkaline environment. The n ‐Si/BDD photoanodes were demonstrated for localized PECL imaging of [Ru(bpy) 3 ] 2+ ‐functionalized magnetic microbeads as an immunoassay‐relevant model system. This work establishes a chemically robust platform for reliable PECL imaging of luminophore‐functionalized beads, highlighting its potential for future bead‐based immunoassay applications and advanced clinical diagnostic technologies.