Novel water/oxygen cycle reaction photo fuel cell for solar conversion and pollutant detection: Based on selective 2-electron collaborative catalysis process

New typed photovoltaic devices, represented by water/oxygen cycle based photo fuel cells (PFCs) as a promising strategy to resolve the fossil energy crisis, have attracted extensive attention for the ideal photo energy conversion and utilization efficiency, spontaneous operation, and miniaturized devices. However, they still have limitations such as low oxygen reduction efficiency and poor stability caused by the complex structure of the cathode. In this work, a synergetic and fast 2-electron water/oxygen cycle reaction based dual-photoelectrode fuel cell (DPFC) is constructed with molecularly imprinted (MI)-CdS/ZnO nanorods (NRs) as photoanode and p-type organic semiconductor polythiophene (pTTh) as photocathode for the first time. The larger self-bias and simple structure endow the device higher open circuit potential (EOCV = 1.07 ± 0.08 V) and ideal output power density (Pmax = 60.5 ± 2.1 μW·cm−2). Attributed to the synergistic reaction effects, the 2-electron water/oxygen cycle is realized by the photocathode-generated H2O2 to serve as shuttle molecule, with outstanding cyclic stability (96 %) in 64 h continuous irradiation. Moreover, a portable self-powered sensor for the typical environmental pollutant atrazine is successfully developed based on this DPFC. A very wide concentration range (0.002 to 50 nM) and a super low detection limit (0.19 pM) is achived via a digital multimeter without the assistance of any signal amplifier. The mechanism, pathway, and active site of the selective reduction process are studied by the attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS). This work has proposed a cheap and regulatable new way to convert and utilize solar energy and provided theoretical guidance for achieving economic power generation and the sensing strategy of self-powered sensors.