Photoelectrochemical Supercontinuum Solar Light Zero Bias Hydrogen Generation with Membrane-Based Cells Designed for Decreasing Overall Water Electrolysis Voltage and Water Dissociation (23)

Abstract

We have created a two-compartment cell (2CC) separated by a bipolar membrane (BPM1) 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).2 The BPMTHEA-2CC has distinguishing characteristics of integrated functionality of dualities, providing an infinite supply of active reaction species, H+ and OH-, from water with an opposite bidirectional charge separation under appropriate applied voltage conditions. We wish to suggest the feasibility of electrochemical water splitting (decomposition) with less than theoretical 1.23 V at RT using an anolyte (water or base)|OER active THE|BPM|HER active THE|catholyte (water or acid). We disprove the theory of water electrolysis established for hundreds of years with sustainable dual CBs. However, we still require external voltage for water electrolysis. Instead of external voltage, we have harnessed solar energy by applying the TH n-type semiconductor photoanodes to BPMTHEA-2CC for a zero-bias photogalvanic cell. Anatase TH TiO2 was used for a model to demonstrate our concept. We succeeded in measuring photocurrent from distilled water with a response of optical shutter. The magnitude of the zero bias photocurrent is proportional to the magnitude of outer CB and illuminance intensity. TH Fe2O3 was prepared by the aqueous chemical growth method. Visible light zero bias photocurrent from distilled water was also observed in the TH Fe2O3 photogalvanic cell without any external voltage. Currently, our research efforts are focused on PEC zero bias hydrogen generation with harnessing supercontinuum solar light by designing optical tandem, wavelength multiplexing with BPMTHEA-2CC and Au plasmon-induced WD. 1) V. J. Frilette, J. Phys. Chem., 60, 435 (1956).2) K. Sakamaki et al., 97th CSJ, 3A6-05 (2017), 68th ISE, Providence, USA, ise171503 (2017), The 22nd Top. Meeting of ISE, Tokyo, abs170627 (2018), 69th ISE, Bologna, Italy, ise183543 (2018). Figure 1