NSF/DOE Solar Hydrogen Fuel: Tunable Semiconductor/Catalyst Interfaces for Efficient Solar WaterSplitting

许多研究都在创造新的材料和工艺，以制造太阳能燃料电池装置，将阳光中的能量转化为燃料(氢和碳氢化合物)，并从可再生原料(水和二氧化碳)中储存。然而，由于燃料电池材料成本高、太阳能到化学转换效率低、不稳定和寿命短，目前还没有这种类型的商业产品。正在向教授颁发奖项。罗格斯大学的查尔斯·迪穆克斯、埃里克·加芬克尔和玛莎·格林布拉特通过美国国家科学基金会和能源部联合发起的太阳能氢气燃料征集计划，创造出新的纳米材料，并以一种特殊的方式将它们结合在一起，制造出一种新的装置，可以绕过这些限制，同时将太阳能的效率提高到原来的两倍。太阳能光伏电池中的新材料将与现有的催化剂集成在一起，制造独立的光驱动电解槽，将水分解成元素，并分别将二氧化碳还原为液体燃料。该装置将以丰富的稀土催化剂为特色，其效率可与现有的铂族催化剂相媲美，但经济和可扩展。新的复合光伏材料的合成将被用作阳极和阴极的太阳能吸收材料，具有互补的光谱覆盖功能，预计将使太阳能到氢的转换效率比目前的系统提高两倍。将设计出将催化剂与太阳能吸收器集成的新方法。这些目标的实现直接关系到美国在环境和能源安全方面的利益。该奖项的目标要求设计新材料，并将它们耦合到新的工作装置中。要实现的具体里程碑是：1)通过使用碱性交换膜作为氢氧化物导电介质，构建串联光电化学电池，将析氧催化剂(立方LiCoO2/离聚体)和析氢催化剂(Ni5P4/离聚体)耦合到(双)带隙吸收体作为光阳极(钙钛矿型氧化物AB3-xNx)和光阴极(pn-硅)，从而实现将当前最先进的太阳能转氢效率提高一倍至10%。2)合成钙钛矿型氧氮化物系列ABO3-xNx中的部分成员，其中A=碱土或稀土阳离子，B=Ti，V，Zr，Nb，Ta，并用B位取代Ti。3)首先通过脉冲激光沉积(PLD)制备上述钙钛矿薄膜，然后在随后的几年中探索其他方法来生长梯度薄膜。4)在添加析氧催化剂之前，表征这些材料的光学带隙和光生载流子寿命。5)用PLD法制备了立方LiCoO2薄膜，它既与光阳极直接接触，又作为中间透明导体的掩埋结。6)在Ni5P4与各种光电阴极(硅和其他低禁带半导体)之间产生稳定的界面，以实现高效的电子捕获以释放氢气。7)在Ni5P4和碱性交换离聚体之间产生稳定的界面，以实现高效的氢氧化物传输、较慢的电荷复合和长期稳定性。8)研究了连接光电极的两种电解液体系：碱性水溶液(PH 14)和碱性交换膜。这些里程碑的实现将代表着该技术的重大进步。

Much research has gone into creating new materials and processes for making solar fuels cell devices that convert and store the energy in sunlight as fuels (hydrogen and hydrocarbons) from renewable feedstocks (water and carbon dioxide). However, no commercial products of this type yet exist due to the high cost of fuel cell materials, low solar to chemical conversion efficiencies, instability and short lifetime. An award is being made to Profs. Charles Dismukes, Eric Garfunkel and Martha Greenblatt of Rutgers University through the joint NSF/DOE Solar H2 Fuel Solicitation to create new nanomaterials and combine them in a special fashion to produce a new device that circumvents these limitations, while increasing the solar efficiency by a factor of 2. The new materials in the solar photovoltaic cells will be integrated with existing catalysts to make standalone light-driven electrolyzers for splitting water into its elements and, separately, reducing carbon dioxide to a liquid fuel. The device will feature earth abundant catalysts that rival the efficiency of existing platinum group catalysts, yet are economical and scalable. Syntheses of new composite photovoltaic materials to be used as solar absorbers for the anode and cathode that feature complementary spectral coverage are predicted to deliver a two-fold increase in solar-to-hydrogen conversion efficiency relative to current systems. New methods for integration of catalysts with solar absorbers will be devised. Attainment of these goals read directly on environmental and energy security benefits to the USA. The goals of this award require the design of new materials and the coupling of them into new working devices. The specific milestones to be achieved are: 1) To achieve a two-fold increase to 10% of the current state-of-the-art solar-to-hydrogen efficiency by constructing a tandem photoelectrochemical cell with catalysts for Oxygen evolution (cubic LiCoO2/ionomer) and Hydrogen evolution (Ni5P4/ionomer) coupled to (dual) bandgap absorbers as photoanode (perovskite oxynitrides ABO3-xNx) and photocathode (pn-silicon), using an alkaline exchange membrane as a hydroxide conducting medium. 2) Synthesize selected members of the perovskite oxynitride series ABO3-xNx where A = alkaline earth or rare earth cation and B = Ti, V, Zr, Nb, Ta, and with B site substitutions Nb or Ta for Ti. 3) Prepare thin films of the foregoing perovskites, first by pulsed laser deposition (PLD), and, in subsequent years, explore other methods to grow gradient films. 4) Characterize the optical bandgaps and photoinduced carrier lifetimes of these materials prior to attaching O2 evolution catalysts. 5) Using PLD, prepare thin films of cubic LiCoO2 both in direct contact with the photoanode and as a buried junction with intervening transparent conductors. 6) Produce stable interfaces between Ni5P4 with various photocathodes (silicon and other low bandgap semiconductors) to achieve efficient electron capture for H2 evolution. 7) Produce stable interfaces between Ni5P4 and alkaline exchange ionomers to achieve efficient hydroxide transport, slower charge recombination, and long term stability. 8) Investigate two electrolyte systems for connecting the photoelectrodes: aqueous alkaline electrolyte solution (pH 14), and alkaline exchange membrane. Achievement of these milestones will represent a significant advance in the technology.