Sandwich-Nanostructured n-Cu₂O/AuAg/p-Cu₂O Photocathode with Highly Positive Onset Potential for Improved Water Reduction

Abstract

An n-Cu 2 O layer formed a high-quality buried junction with p-Cu 2 O to increase the photovoltage and thus to shift the turn-on voltage positively. Mott−Schottky measurements confirmed that the improvement benefited from a positive shift in flat-band potential. The obtained extremely positive onset potential, 0.8 V RHE in n-Cu 2 O/AuAg/p-Cu 2 O, is comparable with measurements from water reduction catalysts. The AuAg alloy sandwiched between the homojunction of n-Cu 2 O and p-Cu 2 O improved the photocatalytic performance. This alloy both served as an electron relay and promoted electron-hole pair generation in nearby semiconductors; the charge transfer between n-Cu 2 O and p-Cu 2 O in the sandwich structure was measured with X-ray absorption spectra. The proposed sandwich structure can be considered as a new direction for the design of efficient solar-related devices.

Charge Transfer-Mediated Blue Luminescence in Plasmonic Ag–Cu2O Quantum Nanoheterostructures

“…The hybrid metal–semiconductor nanoheterostructure is the integration of discrete domains of metal and semiconducting materials within one hybrid nanostructure so that multifunctionalities may be incorporated. Metal–semiconductor hybrid nanoheterostructures are an important class of multicomponent nanosystems that may exhibit not only an amalgamation of properties from the individual components but also further enhanced tunability of different properties together with new synergistic properties that arise essentially from the nanoscale interactions between the distinct metal and semiconductor components at the interfaces. − The interaction of electromagnetic radiation with the metal–semiconductor interfaces at nanoscale causes interesting physical phenomena like surface-enhanced Raman scattering (SERS) and enhanced photoluminescence (PL) effect, which can be used for many device applications, including light-emitting diodes (LEDs), laser diodes (LDs), and photodetectors (PDs). − Improved carrier injection across the metal–semiconductor heterointerfaces can enhance the device performance for LEDs, LDs, and PDs with a high efficiency and a low wavelength drop. The effective charge carrier separation at the interfaces of metal–semiconductor heterostructures can also significantly modify the photocatalytic and gas sensing efficiency. − Being a p-type semiconductor with a direct forbidden band gap ( E g ) of 2.17 eV in its bulk form at room temperature (RT), cuprous oxide (Cu 2 O) attracts considerable attention of researchers due to its very high excitonic binding energy (140 meV at RT), which is many fold larger than the RT thermal energy (26 meV) .…”

In-situ synthesis of Cu2O on cotton fibers with antibacterial properties and reusable photocatalytic degradation of dyes

“…The diffraction peaks observed at 2θ = 29.36 o , 36.45 o , 42.38 o , 61.57 o , 73.69 o and 77.65 o correspond to the (110), (111), (200), (220), (311) and (222) crystal planes of Cu 2 O (JCPDS no: 77-0199) [31] , [32] , respectively, as indicated in the Fig.4 a. This is the XRD diffraction patterns of the crystal structures of octahedral Cu 2 O [33] , [34] . At the same time, the growth of octahedral Cu 2 O in the FE-SEM images was verified ( Fig.…”

Bundle-Type Columnar Cu2O Photoabsorbers with Vertical Grain Boundaries Fabricated Using Instant Strike-Processed Metallic Seeds and Their Enhanced Photoelectrochemical Efficiency

“…The impedance measurements assisted a deeper understanding of the charge transport related to the electrical conductivity. In the Nyquist plots measured in the dark state and fitted with a simple Randle equivalent circuit model, the radius of the apparent semicircle, depicting the total resistance of the PEC systems, is dramatically decreased with the introduction of the instant strike process in the initial electrodeposition of Cu 2 O photocathodes (Figure b) . In addition, the diameter of the second semicircle under light irradiation represents the charge-transfer resistance ( R ct ) at the photoelectrode/electrolyte interfaces (Figure c).…”

“…In the Nyquist plots measured in the dark state and fitted with a simple Randle equivalent circuit model, the radius of the apparent semicircle, depicting the total resistance of the PEC systems, is dramatically decreased with the introduction of the instant strike process in the initial electrodeposition of Cu 2 O photocathodes (Figure 6b). 48 In addition, the diameter of the second semicircle under light irradiation represents the charge-transfer resistance (R ct ) at the photoelectrode/electrolyte interfaces (Figure 6c). This demonstrates that R ct is remarkably decreased with the application of the strike process in the Cu 2 O photocathodes.…”