Abstract: Disclosed is a semiconductor-liquid junction based photoelectrochemical (PEC) cell for the unassisted solar splitting of water into hydrogen and oxygen gas, the solar-driven reduction of CO2 to higher-order hydrocarbons, and the solar-driven synthesis of NH3. The disclosed system can employ a photocathode based upon wurtzite hexagonal semiconductors that can be tailored with proper band alignment for the redox potentials for water, CO2 reduction, and NH3 production, and with bandgap energy for maximum solar absorption. The design maximizes the carrier collection efficiency by leveraging spontaneous and piezoelectric polarization in these materials systems to generate hot electrons within the photocathode. These electrons have sufficient excess energy, preserved at a designed energy capture region, to overcome the kinetic overpotential (surface chemistry limitation) required for the reactions to occur at a high rate.

Abstract: Disclosed is a semiconductor-liquid junction based photoelectrochemical (PEC) cell for the unassisted solar splitting of water into hydrogen and oxygen gas, the solar-driven reduction of CO2 to higher-order hydrocarbons, and the solar-driven synthesis of NH3. The disclosed system can employ a photocathode based upon wurtzite hexagonal semiconductors that can be tailored with proper band alignment for the redox potentials for water, CO2 reduction, and NH3 production, and with bandgap energy for maximum solar absorption. The design maximizes the carrier collection efficiency by leveraging spontaneous and piezoelectric polarization in these materials systems to generate hot electrons within the photocathode. These electrons have sufficient excess energy, preserved at a designed energy capture region, to overcome the kinetic overpotential (surface chemistry limitation) required for the reactions to occur at a high rate.