Advanced flexible photocatalytic fuel cell using TiO2/carbon quantum dots photoanode for green electricity production

Flexible electronics have attracted great attention in recent years. However, the matching power sources of these flexible electronics now are mostly rigid, greatly hindering the way of all-flexible electronics. Here, a flexible photocatalytic fuel cell (fPFC) was designed to produce a stable energy output (highest power density of 40.1 mW·cm−2·g−1 in artificial sweat) while purify wasted water simultaneously. The fPFC is consisted of TiO2/carbon quantum dots (CQDs) photoanode and Ag cathode. The experimental results show that the combination of TiO2 and CQDs can broaden the range of light absorption of TiO2. Thus, the photocurrent density of TiO2/CQDs fPFC can reach up to 252.3 mA·cm−2·g−1, while the photocurrent density of pure TiO2 fPFC is 87.4 mA·cm−2·g−1. The photocurrent density of TiO2/CQDs fPFC is 188.7% higher than that of TiO2 fPFC. The maximum power density of TiO2/CQDs fPFC in flatting state is about 40.1 mW·cm−2·g−1. This TiO2/CQDs fPFC has better performance than fPFC in other literature. Besides, TiO2/CQDs fPFC in the bending state can also achieve a good performance. Four fPFCs can be easily constructed into a bracelet and generate electricity, and there is no significant change in opening voltage under flatting and bending states. This eco-friendly system has great potential in energy conservation and portable electronics, and can be applied in the following aspects: (i) wearable technology that utilizes organic waste for power generation; (ii) flexible configuration of traditional sewage treatment.