Simulations of the irradiation and temperature dependence of the efficiency of tandem photoelectrochemical water-splitting systems
Simulations of the irradiation and temperature dependence of the efficiency of tandem photoelectrochemical water-splitting systems
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DOI：
10.1039/c3ee41302k
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发表时间：
2013-12-01
影响因子：
32.5
通讯作者：
Lewis, Nathan S.
中科院分区：
文献类型：
--
作者：
Haussener, Sophia;Hu, Shu;Lewis, Nathan S.
运行的光电化学太阳能燃料发电机系统的瞬时效率是一个复杂的函数，在光强度和光电压和光电流的温度依赖性之间进行权衡，以及与欧姆电阻、浓度过电位、动力学过电位和质量输运等因素相关的损失。使用先进的光电化学装置模型对这些权衡进行了定量评估，该模型由半导体光吸收器的分析装置物理模型与解决系统其他各个部分的控制守恒方程的多物理装置模型相结合。该模型用于评估由于太阳辐照的小时和季节变化以及由于等温系统温度的变化而引起的系统效率变化。系统的性能特征也被评估为双吸收器串联组件的带隙及其性能，以及器件尺寸和电解质电导率的函数。模拟结果表明，系统效率在白天和一年内变化显著，在正午呈现局部最小值，在年中太阳辐射最强烈时呈现全球最小值。这些变化可以通过选择合适的系统尺寸、降低电解质的欧姆电阻和/或使用非常活跃的电催化剂进行燃料生成反应来减小。系统温度的升高降低了年平均效率，导致系统的上升和下降阶段的速度减慢，但减少了正午和年中瞬时效率的变化。系统尺寸的仔细选择导致系统效率的最小变化，以响应光吸收材料质量的退化。优化的集成系统的日和年平均产氢质量优于由电连接到独立电解槽系统的优化的独立串联光伏阵列产生的日和年平均产氢质量。该模型可用于预测系统的性能，优化太阳能驱动水分解装置的设计，指导装置部件和系统整体的发展。
The instantaneous efficiency of an operating photoelectrochemical solar-fuel-generator system is a complicated function of the tradeoffs between the light intensity and temperature-dependence of the photovoltage and photocurrent, as well as the losses associated with factors that include ohmic resistances, concentration overpotentials, kinetic overpotentials, and mass transport. These tradeoffs were evaluated quantitatively using an advanced photoelectrochemical device model comprised of an analytical device physics model for the semiconducting light absorbers in combination with a multi-physics device model that solved for the governing conservation equations in the various other parts of the system. The model was used to evaluate the variation in system efficiency due to hourly and seasonal variations in solar irradiation as well as due to variation in the isothermal system temperature. The system performance characteristics were also evaluated as a function of the band gaps of the dual-absorber tandem component and its properties, as well as the device dimensions and the electrolyte conductivity. The modeling indicated that the system efficiency varied significantly during the day and over a year, exhibiting local minima at midday and a global minimum at midyear when the solar irradiation is most intense. These variations can be reduced by a favorable choice of the system dimensions, by a reduction in the electrolyte ohmic resistances, and/or by utilization of very active electrocatalysts for the fuel-producing reactions. An increase in the system temperature decreased the annual average efficiency and led to less rapid ramp-up and ramp-down phases of the system, but reduced midday and midyear instantaneous efficiency variations. Careful choice of the system dimensions resulted in minimal change in the system efficiency in response to degradation in the quality of the light absorbing materials. The daily and annually averaged mass of hydrogen production for the optimized integrated system compared favorably to the daily and annually averaged mass of hydrogen that was produced by an optimized stand-alone tandem photovoltaic array connected electrically to a stand-alone electrolyzer system. The model can be used to predict the performance of the system, to optimize the design of solar-driven water splitting devices, and to guide the development of components of the devices as well as of the system as a whole.