Solution-processed GaSe nanoflake-based films for photoelectrochemical water splitting and photoelectrochemical-type photodetectors

Marilena Isabella Zappia; Gabriele Bianca; Sebastiano Bellani; Michele Serri; Leyla Najafi; Reinier Oropesa-Nuñez; Beatriz Martín-García; Daniel Bouša; David Sedmidubský; Vittorio Pellegrini; Zdeněk Sofer; Anna Cupolillo; Francesco Bonaccorso

doi:10.1002/adfm.201909572

arXiv · 2004.10034

Solution-processed GaSe nanoflake-based films for photoelectrochemical water splitting and photoelectrochemical-type photodetectors

Marilena Isabella Zappia·Gabriele Bianca·Sebastiano Bellani·Michele Serri·Leyla Najafi·Reinier Oropesa-Nuñez·Beatriz Martín-García·Daniel Bouša·David Sedmidubský·Vittorio Pellegrini·Zdeněk Sofer·Anna Cupolillo·Francesco Bonaccorso

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Abstract

Gallium selenide (GaSe) is a layered compound, which has been exploited in nonlinear optical applications and photodetectors due to its anisotropic structure and pseudo-direct optical gap. Theoretical studies predicted that its two-dimensional (2D) form is a potential photocatalyst for water splitting reactions. Herein, we first report the photoelectrochemical (PEC) characterization of GaSe nanoflakes (single-/few-layer flakes), produced via liquid phase exfoliation, for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in both acidic and alkaline media. In 0.5 M H2SO4, the GaSe photoelectrodes display the best PEC performance, i.e. a ratiometric power-saved metric for HER ({\Phi}saved,HER) of 0.09% and a ratiometric power-saved metric for OER ({\Phi}saved,OER) of 0.25%. When used as PEC-type photodetectors, GaSe photoelectrodes show a responsivity of ~0.16 A W-1 upon 455 nm illumination at light intensity of 63.5 uW cm-2 and applied potential of -0.3 V vs. reversible hydrogen electrode (RHE). The stability analysis of the GaSe photodetectors evidences a durable operation over tens of cathodic linear sweep voltammetry scans in 0.5 M H2SO4 for HER. Viceversa, degradation effects have been observed in both alkaline and anodic operation due to highly oxidizing environment and O2-induced (photo-)oxidation effects. Our results provide new insight into PEC properties of GaSe nanoflakes for their exploitation in photoelectrocatalysis, PEC-type photodetectors and (bio)sensors.

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Marilena Isabella Zappia, Gabriele Bianca, Sebastiano Bellani, Michele Serri, Leyla Najafi, Reinier Oropesa-Nuñez, Beatriz Martín-García, Daniel Bouša, David Sedmidubský, Vittorio Pellegrini, Zdeněk Sofer, Anna Cupolillo, Francesco Bonaccorso. 2020-04-21. Solution-processed GaSe nanoflake-based films for photoelectrochemical water splitting and photoelectrochemical-type photodetectors. https://doi.org/10.1002/adfm.201909572

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