Surface Assistant Charge Separation in PEC Cu₂S-Ni/Cu₂O Cathode

Area of Science:

• Materials Science
• Electrochemistry
• Photocatalysis

Background:

• Developing high-efficiency photocathodes is crucial for advancing photoelectrocatalysis (PEC).
• Existing photocathode materials often face limitations in charge separation and catalytic activity.

Purpose of the Study:

• To construct and characterize a novel Cu₂S-Ni/Cu₂O photocathode for improved PEC performance.
• To investigate the role of Nickel (Ni) incorporation on the photocathode's morphology, charge dynamics, and catalytic activity.

Main Methods:

• Fabrication of Cu₂S-Ni/Cu₂O photocathode using electrodeposition, direct-current magnetron sputtering (DCMS), and ion exchange.
• Material characterization using X-ray Photoelectron Spectroscopy (XPS).
• Electrochemical and photophysical analysis including Electrochemical Impedance Spectroscopy (EIS), Tafel slopes, Photoluminescence (PL) spectra, and Surface Photovoltage Microscopy (SPVM).

Main Results:

• The Ni inner-layer enhanced the formation rate and morphology of the outer Cu₂S layer; Ni was present as NiO.
• The Cu₂S-Ni/Cu₂O photocathode exhibited a photocurrent density twice that of the pristine Cu₂O.
• Ni promoted the hydrogen evolution reaction via the Heyrovsky mechanism, while Cu₂S improved surface charge separation.

Conclusions:

• The integrated Cu₂S-Ni/Cu₂O structure effectively enhances photoelectrocatalytic hydrogen evolution.
• Ni incorporation plays a key role in promoting catalytic activity and facilitating charge transfer.
• SPVM provided direct evidence of the charge transport pathway, elucidating the function of each component.