Strong interest exists in the development of organic-inorganic lead halide perovskite photovoltaics and of photoelectrochemical (PEC) tandem absorber systems for solar fuel production. However, their scalability and durability have long been limiting factors. In this work, we reveal how both fields can be seamlessly merged together, to obtain scalable, bias-free solar water splitting tandem devices. For this purpose, state-of-the-art cesium formamidinium methylammonium (CsFAMA) triple cation mixed halide perovskite photovoltaic cells with a nickel oxide (NiO x) hole transport layer are employed to produce Field's metal-epoxy encapsulated photocathodes. Their stability (up to 7 h), photocurrent density (-12.1±0.3 mA cm −2 at 0 V vs. RHE) and reproducibility enables a matching combination with robust BiVO 4 photoanodes, resulting in 0.25 cm 2 PEC tandems with an excellent stability of up to 20 h and a bias-free solar-to-hydrogen efficiency of 0.35±0.14%. The high reliability of the fabrication procedures allows scaling of the devices up to 10 cm 2 , with a slight decrease in bias-free photocurrent density from 0.39±0.15 mA cm −2 to 0.23±0.10 mA cm −2 due to an increasing series resistance. To characterise these devices, a versatile 3D-printed PEC cell was also developed. The modular PEC cell represents an affordable alternative to existing designs and can be easily adjusted for a broad range of samples. Overall, these findings shed further light on the factors required to bring both perovskite photovoltaics and photoelectrocatalysis into large-scale applications, revealing some key aspects for device fabrication, operation and implementation.

Solar-driven reforming uses sunlight and a photocatalyst to generate H 2 fuel from waste at ambient temperature and pressure. However, it faces practical scaling challenges such as photocatalyst dispersion and recyclability, competing light absorption by the waste solution, slow reaction rates and low conversion yields. Here, the immobilisation of a noble-metalfree carbon nitride/nickel phosphide (CN x j Ni 2 P) photocatalyst on textured glass is shown to overcome several of these limitations. The 1 cm 2 CN x j Ni 2 P panels photoreform plastic, biomass, food and mixed waste into H 2 and organic molecules with rates comparable to those of photocatalyst slurries. Furthermore, the panels enable facile photocatalyst recycling and novel photoreactor configurations that prevent parasitic light absorption, thereby promoting H 2 production from turbid waste solutions. Scalability is further verified by preparing 25 cm 2 CN x j Ni 2 P panels for use in a custom-designed flow reactor to generate up to 21 μmol H 2 m À 2 h À 1 under "real-world" (seawater, low sunlight) conditions. The application of inexpensive and readily scalable CN x j Ni 2 P panels to photoreforming of a variety of real waste streams provides a crucial step towards the practical deployment of this technology.

Extrapolating the properties of individual CNTs into macro-scale CNT materials using a continuous and cost effective process offers enormous potential for a variety of applications.The floating catalyst chemical vapor deposition (FCCVD) method discussed in this paper bridges the gap between generating nano-and macro-scale CNT material and has already been adopted by industry for exploitation. A deep understanding of the phenomena occurring within the FCCVD reactor is thereby key to producing the desired CNT product and successfully scaling up the process further. This paper correlates information on decomposition of reactants, axial catalyst nanoparticle dynamics and the morphology of the resultant CNTs and shows how these are strongly related to the temperature and chemical availability within the reactor. For the first time, in-situ measurements of catalyst particle size distributions coupled with reactant decomposition profiles and a detailed axial SEM study of formed CNT materials reveal specific domains that have important implications for scale-up.A novel observation is the formation, disappearance and reformation of catalyst nanoparticles along the reactor axis, caused by their evaporation and re-condensation and mapping of different CNT morphologies as a result of this process.

Electrolyzers combining CO2 reduction (CO2R) with organic substrate oxidation can produce fuel and chemical feedstocks with a relatively low energy requirement when compared to systems that source electrons from water oxidation. Here, we report an anodic hybrid assembly based on a (2,2,6,6‐tetramethylpiperidin‐1‐yl)oxyl (TEMPO) electrocatalyst modified with a silatrane‐anchor (STEMPO), which is covalently immobilized on a mesoporous indium tin oxide (mesoITO) scaffold for efficient alcohol oxidation (AlcOx). This molecular anode was subsequently combined with a cathode consisting of a polymeric cobalt phthalocyanine on carbon nanotubes to construct a hybrid, precious‐metal‐free coupled AlcOx–CO2R electrolyzer. After three‐hour electrolysis, glycerol is selectively oxidized to glyceraldehyde with a turnover number (TON) of ≈1000 and Faradaic efficiency (FE) of 83 %. The cathode generated a stoichiometric amount of syngas with a CO:H2 ratio of 1.25±0.25 and an overall cobalt‐based TON of 894 with a FE of 82 %. This prototype device inspires the design and implementation of nonconventional strategies for coupling CO2R to less energy demanding, and value‐added, oxidative chemistry.

A triphasic photocatalytic reactor employing a mesoporous carbon nitride photocatalyst and aerobic O2 was assembled to operate under continuous flow conditions. This reactor design allows for facile downstream processing and reusability in multiple flow cycles. The selective aerobic oxidation of alcohols and amines was chosen to demonstrate the applicability and performance advantage of this flow approach compared to conventional batch photochemistry. This precious-metal-free photocatalytic flow system operates under benign reaction conditions (visible light, low pressure, and mild temperature) and will stimulate the exploration of other oxidative reactions in a sustainable, scalable, and affordable manner.