Photoelectrochemical Activity of Layered Metal Phosphorous Trichalcogenides for Water Oxidation

2D layered materials are currently one of the most explored materials in developing efficient and stable photoelectrocatalysts in energy conversion applications. Some of the 2D metal phosphorus chalcogenides (M2P2X6 or plainly MPX3) have been reported to be useful catalysts for water splitting. Herein, the photoresponsivity of a series of synthesized M2P2X6 (M2+ = Mn, Fe, Co, Zn, Cd; X = S, Se), tested for the oxygen evolution reaction (OER) region in alkaline media, with excitation wavelengths from 385 to 700 nm, is reported. The experimentally determined optical bandgaps of the MPX3 materials range from 1.5 eV for FePSe3 to 3.7 eV for ZnPS3. At +1.23 V versus reversible hydrogen electrode (RHE), the photoelectrochemical (PEC) activity in the OER region of MnPSe3 exhibits superior performance, while the exfoliation of CoPS3 improves its PEC activity up to double in contrast with its bulk counterpart. The influence of the substrate (glassy carbon (GC), indium tin oxide (ITO), and aluminum-doped zinc oxide (AZO)) and applied potential is also studied. Exfoliated CoPS3 reaches a photoresponsivity of up to 0.6 mA W-1 under 450 nm excitation wavelength and at +1.23 V versus RHE in alkaline electrolyte.

Automated summary

2D layered materials, specifically metal phosphorus chalcogenides, are being extensively studied for their potential as photoelectrocatalysts in energy conversion applications, particularly in water splitting. The experimentally determined optical bandgaps of these materials vary from 1.5 eV to 3.7 eV. Among them, MnPSe3 shows superior performance in the oxygen evolution reaction region, while exfoliated CoPS3 demonstrates doubled photoelectrochemical activity compared to its bulk counterpart. The substrate and applied potential have significant influences on the photoresponsivity of these materials, with exfoliated CoPS3 achieving a photoresponsivity of up to 0.6 mA W-1 under specific conditions.