Enhanced charge transfer kinetics of Fe2O3/CdS composite nanorod arrays using cobalt-phosphate as cocatalyst

- Ternary Fe2O3/CdS/Co-Pi nanorod arrays photoanode was successfully fabricated.
- Charge transfer kinetics were greatly promoted after depositing CdS and Co-Pi.
- Much lower onset potential needed to generate photocurrent after depositing Co-Pi.
- High saturated photocurrent density achieved for Fe2O3/CdS/Co-Pi photoanode.
- Synergistic effect of CdS and Co-Pi contributes to the superior PEC activity.

Photoelectrochemical (PEC) water splitting is one of the most efficient strategies to meet the challenges of the global energy crisis. Although hematite (α-Fe2O3), is a suitable material for PEC, its performance is limited by passive surface state and slow charge transfer kinetics. Here, a successful design and fabrication of novel ternary Fe2O3/CdS/Co-Pi nanorod arrays (NRAs) photoanode is reported aimed at boosting charge separation and transfer kinetics within the bulk and at the electrode/electrolyte interface. As expected, the results reveal that α-Fe2O3 sluggish reaction kinetics is greatly ameliorated upon depositing CdS and Co-Pi, and surface charge recombination decreases even more, resulting in substantially enhanced photocurrent density. Moreover, noticeable onset potential negative shift evidenced by the I-V curve is found to result from the deposition of CdS and Co-Pi, which allows the ternary composite to generate photocurrent at much lower applied potential. We elaborate the synergistic effect of CdS and Co-Pi in achieving faster charge transfer kinetics and lower onset potential for photocurrent. These results provide new insights into the surface reaction kinetics of Co-Pi/semiconductor photoanode toward PEC application.

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