Author: Xiangjiu Guan (State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University) - Photocatalytic (sea)water splitting can convert the abundant solar energy into chemical energy in the form of hydrogen for stable storage and clean utilization. Nevertheless, the current solar-to-hydrogen conversion efficiency is still relatively low, due to limited solar spectrum absorption, with the energy of long-wavelength photons not properly utilized and wasted in the form of heat. In order to achieve full-spectrum driven hydrogen production, we developed novel strategy and corresponding device for the utilization of waste heat from photocatalytic (sea)water splitting. By blocking the direct convection heat transfer between reaction system and external environment, the temperature of reacting solution could be elevated, hence boosting the performance of photothermal catalytic hydrogen production. Further introducing thermoelectric device could help to convert the heat into electricity, achieving hydrogen-electricity coproduction, and the self-storage heat capacity of the solid-liquid phase reaction system could facilitate continuous power generation without light irradiation. When coupling phase-change material on the cold side of thermoelectric device, storage of waste heat was achieved and the system could sustain all-day operation for hydrogen production and power generation. Moreover, through optimizing the heat conversion process, the solar-to-hydrogen conversion efficiency in seawater splitting system was significantly enhanced, providing a valuable technical approach for the efficient conversion and utilization of solar energy.
