Philipp Huth

Solid molecular catalysts (SMCs) represent a promising class of photocatalysts. Here, we report the influence of distinct donor and acceptor moieties of terpyridine‐based SMCs on the photocatalytic hydrogen peroxide (H ₂ O ₂ ) production. An aromatic and linear donor proved to be advantageous due to its favorable optoelectrical properties, achieving an activity of 8.55 mmol g ⁻¹ h ⁻¹ under white light irradiation without any sacrificial agents. The variation of backbone functionalities (toluene (C), pyrrole (N), furan (O), and thiophene (S)) revealed the important role of charge stabilization in the acceptor units through inductive and mesomeric effects. Scaling up the reaction with the best performing SMC C2‐SP1 yielded a photocatalytic activity of 12.8 mmol g ⁻¹ h ⁻¹ (405 nm). To facilitate the transition from laboratory studies to practical applications, H ₂ O ₂ production has been successfully demonstrated under natural sunlight. Under optimized reaction conditions, concentrations of up to 108.3 mg L ⁻¹ were achieved, demonstrating the potential of SMCs for sustainable hydrogen peroxide generation.

Efficient utilization of solar energy remains paramount in the context of a more sustainable future. To enable rational design of heterogeneous photocatalysts, a deeper understanding of photoactive structures and reaction mechanisms is required. In this study, a modular semiconductor design platform along the axes of pyridine denticity and an amine functionalization is presented. In the model photocatalytic hydrogen peroxide synthesis, the best-performing catalyst achieves productivities upwards of 2.3 mmol h ^-1  g ^-1 under white light irradiation at 500 W m ^-2 . Through application as a coating, both apparent quantum yields (1.27%) and solar-to-chemical conversion efficiencies (0.28%) were significantly improved. In radical scavenging and EPR experiments, the modular design approach allows the correlation of catalyst structures with the formation of different radical species, and in turn, mechanistic pathways. On the basis of this knowledge, the decomposition of waste antibiotics is identified and demonstrated as suitable use-case. This work provides a template for the informed design of photocatalysts and the characterization of the underlying reaction mechanisms.

Efficient utilization of solar energy remains paramount in the context of a more sustainable future. To enable rational design of heterogeneous photocatalysts, a deeper understanding of photoactive structures and reaction mechanisms is required. In this study, a modular semiconductor design platform along the axes of pyridine denticity and an amine functionalization is presented. In the model, photocatalytic hydrogen peroxide production, the best-performing catalyst achieves productivities upwards of 2.3 mmol mmol h-1 g-1 under white light irradiation at 500 W m-2. Through application as a coating, both apparent quantum yields (1.27%) and solar-to-chemical conversion efficiencies (0.28%) were significantly improved. In radical scavenging experiments, the modular design approach allows the correlation of catalyst structures with the formation of different radical species, and in turn, mechanistic pathways. On the basis of this knowledge, the decomposition of waste organics is identified and demonstrated as suitable use-case. This work provides a template for the informed design of photocatalysts and the characterization of the underlying reaction mechanisms.

The development of efficient and environmentally friendly plant protection systems is one of the major challenges for a sustainable agriculture of the future. Citrus canker caused by the pathogen Xanthomonas citri subsp. citri (X. citri) affects all cultivated citrus species worldwide and is responsible for enormous economic losses and restrictions in international trade. Currently used commercial copper‐based formulations are the origin of contamination for soil and groundwater, affecting local ecosystems and human health. A copper‐free sustainable microgel‐based plant protection system able to efficiently combat X. citri is developed. Microgels decorated with anchor peptides exhibit strong non‐covalent attachment to the surface of orange leaves and have the ability to release hexyl gallate, which inhibits the growth and spreading of pathogens. The tailored design of the microgel network allows high loadings of hexyl gallate (up to 40 wt.%) and a controlled release of gallates from microgels that provide long‐term protection. The antibacterial activity of the hexyl gallate‐loaded microgels is demonstrated by various in vitro assays as well as on orange plants in greenhouse settings. The experimental results suggest that the developed sustainable microgel‐based plant protection system for citrus trees allows efficient abatement of X. citri and reduces environmental pollution caused by copper formulations.

In this work, we present a methodology for the real-time monitoring of light induced reactions. Employing process analytical technology (PAT) permits an in situ approach to disclose kinetic insights into photocatalytic reactions. The applicability of this methodology was tested on the eosin Y (EY) catalysed photooxidation of 4-methoxythiophenol (4-MTP) to bis(4-methoxyphenyl)disulfide (4-MPD). The reaction was monitored by in situ Raman and UV/Vis spectroscopy under various process conditions including the stirrer speed, oxygen pressure, EY concentration and light intensity. Evaluation by an indirect hard modelling approach (IHM) disclosed the contributions of rate limiting effects like the oxygen mass transport and the degradation of EY. Detailed investigations on the influence of EY concentration and light intensity led to an empirical model for the correlation of the initial photooxidation rate with the averaged rate of photon absorption. These results confirmed the applicability of the methodology to support the development of photocatalytic reactions.