(Invited) Photoelectrochemical Hydrogen Generation Derived from Water Dissociation Under Supercontinuum Solar Light (25)

摘要

We created a two-compartment cell (2CC) separated by a bipolar membrane (BPM) sandwiched between through-holed electrodes (THEs) assembly (BPMTHEA-2CC) based on the Golden Role for sustainable water splitting derived from water dissociation (WD) with a dual chemical bias (CB). The BPMTHEA-2CC provides an infinite supply of active reaction species, H~+ and OH~-, from water with an opposite bidirectional charge separation under appropriate applied voltage conditions. We have achieved hydrogen generation derived from WD with BPMTHEA-2CC using an oxygen evolving reaction active TH dimensionally stable anode (De Nora Permelec Ltd) prepared on Pt gauze. Liberated gas was analyzed using a gas chromatograph equipped with a MS-5A column and a thermal conductive detector (TCD). We succeeded in detecting appropriate amounts of molecular hydrogen generated in the cathode of a large-sized BPMTHEA-2CC, anolyte (water)|TH anode|BPM|TH cathode|catholyte (water), by imposing a voltage with less than the theoretical 1.23 V for water splitting at room temperature. We disprove the theory of water electrolysis established for hundreds of years. However, we still require external voltage for water electrolysis. Instead of external voltage, we have harnessed supercontinuum solar light throughout by designing optical tandem, wavelength multiplexing. Zero-bias photocurrent was observed by applying TH n-type semiconductor photoanodes to BPMTHEA-2CC. WD at the junction of BPM is considered to be originated in second Wien effect. Thus Au nanoparticle (Au-NP) was introduced into the junction of BPM to carry out plasmon-induced (PI) WD. With mixing different sizes of Au NPs, a wide range of absorption wavelengths would be attainable. Preliminary results obtained using Au-NP modified BPMTHEA-2CC were reported with two plausible mechanisms. A simple 4-port chamber has been developed to measure hydrogen concentrations down to 7.5 ppm and was used to demonstrate PEC zero bias hydrogen generation with harnessing supercontinuum solar light.