High-performance and stable photoelectrochemical water splitting cell with organic-photoactive-layer-based photoanode

Je Min Yu,Jungho Lee,Ja Hun Kwak,Ji-Wook Jang,Changduk Yang,Jaejung Song,Sang Myeon Lee,Jiyeon Oh,Yongseon Kim,Mingyu Jeong,Seungho Cho,Yoon Seo Kim

doi:10.1038/s41467-020-19329-0

Abstract

Considering their superior charge-transfer characteristics, easy tenability of energy levels, and low production cost, organic semiconductors are ideal for photoelectrochemical (PEC) hydrogen production. However, organic-semiconductor-based photoelectrodes have not been extensively explored for PEC water-splitting because of their low stability in water. Herein, we report high-performance and stable organic-semiconductors photoanodes consisting of p-type polymers and n-type non-fullerene materials, which is passivated using nickel foils, GaIn eutectic, and layered double hydroxides as model materials. We achieve a photocurrent density of 15.1 mA cm−2 at 1.23 V vs. reversible hydrogen electrode (RHE) with an onset potential of 0.55 V vs. RHE and a record high half-cell solar-to-hydrogen conversion efficiency of 4.33% under AM 1.5 G solar simulated light. After conducting the stability test at 1.3 V vs. RHE for 10 h, 90% of the initial photocurrent density are retained, whereas the photoactive layer without passivation lost its activity within a few minutes.

Highlights

Considering their superior charge-transfer characteristics, easy tenability of energy levels, and low production cost, organic semiconductors are ideal for photoelectrochemical (PEC) hydrogen production
Ruan et al.[30] and Peng et al.[31] showed the possibility of usage of carbon nitride materials as photoanodes. These organic photoactive-layer-based photoanodes exhibited photocurrent densities of only few microampere scales at 1.23 V vs. reversible hydrogen electrode (RHE) (~100 μA cm−2) but halfcell STH conversion efficiencies were lower than 0.03% so far (Supplementary Table 1 and Supplementary Fig. 1). They lost their performances in a few minutes and even for the case of recent stable organic photoelectrodes stabilized by TiO2 layers, less than 50% initial photocurrent is maintained after 1 h21
The most important mission here is how an organic semiconductor-based photoactive layer is effectually shielded from water while maintaining an efficient charge transfer from organic photovoltaics (OPVs) to water

Summary

Introduction

Considering their superior charge-transfer characteristics, easy tenability of energy levels, and low production cost, organic semiconductors are ideal for photoelectrochemical (PEC) hydrogen production. The photoelectrochemical (PEC) water splitting technology is considered one of the most promising H2 production methods because it utilizes the unlimited energy source of solar light and does not emit CO21 In addition to their sufficient earth abundance and stability in water, photoelectrode materials must exhibit solar-to-hydrogen (STH) conversion efficiency of above 10% for their commercial viability[2]. Ruan et al.[30] and Peng et al.[31] showed the possibility of usage of carbon nitride materials as photoanodes These organic photoactive-layer-based photoanodes exhibited photocurrent densities of only few microampere scales at 1.23 V vs reversible hydrogen electrode (RHE) (~100 μA cm−2) but halfcell STH conversion efficiencies (ηhalf-STH) were lower than 0.03% so far (Supplementary Table 1 and Supplementary Fig. 1). They lost their performances in a few minutes and even for the case of recent stable organic photoelectrodes stabilized by TiO2 layers, less than 50% initial photocurrent is maintained after 1 h21

Methods

Results

Conclusion