ScholarWorks@숙명여자대학교

초록

Ammonia (NH3) oxidation reaction (AOR) has received great interest in recent years as an effective method to enable highly sustainable hydrogen (H2) storage and conversion. Here, we demonstrate an intensively enhanced photoelectrochemical (PEC) AOR-boosted H2 production with a highly activated bismuth-vanadium oxyhydroxide overlayer, derived from an overlaid thin phosphate layer, on BiVO4 (BVO) photoanode. A simple electrochemical (EC) activation is applied on a phosphate-modified bismuth vanadate (Pi-BVO) film to achieve the bimetallic oxyhydroxide overlayer on BVO (a-Pi-BVO) photoanode, which provides a high activity for enhancing the AOR kinetics. We confirm that the a-Pi-BVO photoanode follows pseudo-first order kinetics and demonstrates a 10-fold increase in PEC AOR kinetics, compared to pristine BVO at 0.77 V vs. reversible hydrogen electrode (RHE) in a dilute (500 ppm) NH3 aqueous media. In our solar-assisted overall ammonia electrolysis cell system with 2-electrode configuration, composed of PEC ammonia oxidation and EC hydrogen evolution reactions, a-Pi-BVO photoanode shows a 6.5-fold enhancement in H2 production compared to pristine BVO photoanode. This study demonstrates that the simple surface activation of the Pi-BVO photoanode enables highly active PEC AOR for efficient H2 production under dilute ammonia conditions, which is a promising strategy with applicability to practical wastewater applications.

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