Development of catalysts, namely manganese oxides and molybdenum sulphides, for an implementation in a light-driven water-splitting device using a multi-junction solar cell

该项目旨在寻找不含贵金属的催化剂，适用于光驱动装置，用于从水中生产氢气，作为一种“太阳能燃料”。所设想的装置包括：a)用于水氧化催化的无定形Mn氧化物，b)用于催化质子还原的Mo硫化物，以及c)用于光诱导产生电位差的多结半导体系统。结构和功能研究将促进知识导向的催化剂优化，这些催化剂是金属酶的功能模拟物，在其他水分解系统中也有很高的应用价值。我们的目标是生物启发，因此不含贵金属的催化剂，这可以促进大规模应用，而不受原材料稀缺的阻碍。采用电化学与光谱学相结合的方法对阳极催化剂和阴极催化剂分别进行了研究。用x射线吸收光谱（XAS）研究了非晶态催化剂的原子结构和氧化态。作为一个原理证明，一个完整的混合电池将被组装和研究。我们第一个资助期的主要重点是在惰性电极上沉积的mn基OER（析氧反应）和mosx基HER（析氢反应）电催化剂的结构-活性关系的基本见解。在第二个资助期，我们计划继续使用现在建立的组合(i)催化剂合成，（ii）功能表征，（iii）原子结构研究，以及（iv）光伏测试系统中的催化剂操作。我们将继续进行一项研究策略，旨在获得基本见解，而不仅仅是经验催化剂和设备优化，但将把重点转向匹配催化剂材料与太阳能电池的要求。我们第二个资助期的中心目标是：(1)以知识为导向的mn基OER和mosx基HER催化剂改性，以改善与辐照多结太阳能电池的电流电压特性的相容性；(2)改进了电催化剂在太阳能电池组件接触层上稳定固定（沉积）的方法；(3)深入了解高效OER和HER电催化所需的电解质，重点关注pH值、质子接受离子的作用以及与光伏系统的兼容性；(4)由三结光伏电池和基于锰和钼的地球丰富催化剂材料组成的光驱动h2生成测试系统的运行。

This project aims at precious-metal-free catalysts suitable for implementation in a light-driven device for producing H2, as a 'solar fuel', from water. The envisioned device comprises: a) amorphous Mn oxides for water oxidation catalysis, b) Mo sulphides for catalysis of proton reduction, and c) a multi-junction semiconductor system for light-induced generation of an electrical potential difference. Structural and functional investigations will facilitate a knowledge-guided optimisation of the catalysts, which are functional mimics of metalloenzymes and of high interest also for employment in other water-splitting systems. We are aiming at bio-inspired and thus precious-metal-free catalysts, which could facilitate large-scale application unhindered by raw-material scarcity. The anodic and cathodic catalysts are investigated separately by combining electrochemistry with spectroscopy. Atomic structures and oxidation states of the mostly amorphous catalysts are investigated X-ray absorption spectroscopy (XAS). As a proof-of-principle, a complete hybrid cell will be assembled and studied. Our main focus of the first funding period has been basic insights in structure-activity relations of Mn-based OER (oxygen evolution reaction) and MoSx-based HER (hydrogen evolution reaction) electrocatalysts deposited on inert electrodes. In the second funding period, we plan to go ahead using the now established combination of (i) catalyst synthesis, (ii) functional characterisation, (iii) investigation of the atomic structure, and (iv) catalyst operation in a photovoltaic test system. We will continue with a research strategy that aims at basic insights rather than merely empirical catalyst and device optimisation, but will shift focus towards matching the requirements of the catalyst materials with those of the solar-cell. Our central objectives for the second funding period are: (1) knowledge-guided catalyst modification of Mn-based OER and MoSx-based HER catalysts for improved compatibility with the current-voltage properties of an irradiated multi-junction solar cell; (2) improved methods for the stable immobilisation (deposition) of the electrocatalysts on the contact layers of the solar cell assembly; (3) insights into the electrolyte requirements for efficient OER and HER electrocatalysis with focus on the role of pH regime, proton-accepting ions, and compatibility with the photovoltaic system; (4) operation of test systems for light-driven H2-formation comprising triple-junction PV cells and earth-abundant catalyst materials based on manganese and molybdenum.