“Although the same basics of photocatalysis unite applications in artificial photosynthesis, photoreformation, photoredox catalysis and photodynamic therapy, they are being developed in surprising ...isolation. … This editorial is a call to join forces and embrace progress in all of these areas to enable accelerated development of a more holistic science in photocatalysis. …” Read more in the Guest Editorial by E. Reisner.
With over 8 billion tons of plastic produced since 1950, polymers represent one of the most widely usedand most widely discardedmaterials. Ambient-temperature photoreforming offers a simple and ...low-energy means for transforming plastic waste into fuel and bulk chemicals but has previously only been reported using precious-metal- or Cd-based photocatalysts. Here, an inexpensive and nontoxic carbon nitride/nickel phosphide (CN x |Ni2P) photocatalyst is utilized to successfully reform poly(ethylene terephthalate) (PET) and poly(lactic acid) (PLA) to clean H2 fuel and a variety of organic chemicals under alkaline aqueous conditions. Ni2P synthesized on cyanamide-functionalized carbon nitride is shown to promote efficient charge separation and catalysis, with a photostability of at least 5 days. The real-world applicability of photoreforming is further verified by generating H2 and organics from a selection of nonrecyclable wasteincluding microplastics (polyester microfibers) and food-contaminated plasticand upscaling the system from 2 to 120 mL while maintaining its efficiency for plastic conversion.
This review presents a comprehensive summary of the recent development in semi-artificial photosynthesis, a biological-material hybrid approach to solar-to-chemical conversion that provides new ...concepts to shape a sustainable future fuelled by solar energy. We begin with a brief introduction to natural and artificial photosynthesis, followed by a discussion of the motivation and rationale behind semi-artificial photosynthesis. Then, we summarise how various enzymes can be combined with synthetic materials for light-driven water oxidation, H
2
evolution, CO
2
reduction, and chemical synthesis more broadly. In the following section, we discuss the strategies to incorporate microorganisms in photocatalytic and (photo)electrochemical systems to produce fuels and chemicals with renewable sources. Finally, we outline emerging analytical techniques to study the bio-material hybrid systems and propose unexplored research opportunities in the field of semi-artificial photosynthesis.
This review provides an overview of the cross-disciplinary field of semi-artificial photosynthesis, which combines strengths of biocatalysis and artificial photosynthesis to develop new concepts and approaches for solar-to-chemical conversion.
Photocatalytic reforming of lignocellulosic biomass is an emerging approach to produce renewable H2. This process combines photo‐oxidation of aqueous biomass with photocatalytic hydrogen evolution at ...ambient temperature and pressure. Biomass conversion is less energy demanding than water splitting and generates high‐purity H2 without O2 production. Direct photoreforming of raw, unprocessed biomass has the potential to provide affordable and clean energy from locally sourced materials and waste.
Photocatalytic reforming of lignocellulosic biomass is a promising approach to produce renewable H2 at ambient temperature and pressure. Direct photoreforming of raw, unprocessed biomass is emerging as a potential technology to provide affordable, clean energy from abundant waste.
Solar-driven reforming of plastics offers a simple and low-energy means to turn waste into H2. Here, we report the efficient photoreforming of three commonly produced polymers – polylactic acid, ...polyethylene terephthalate (PET) and polyurethane – using inexpensive CdS/CdOx quantum dots in alkaline aqueous solution. This process operates under ambient temperature and pressure, generates pure H2 and converts the waste polymer into organic products such as formate, acetate and pyruvate. We further validate the real-world applicability of the system by converting a PET water bottle into H2. This is the first demonstration of visible light-driven, noble metal-free photoreforming of plastic.
Cyanamide functionalised carbon nitride powder is reported as a photocatalyst for direct Minisci-type coupling of heteroarenes with ethers, alcohols, and amides using atmospheric oxygen as the ...oxidant at room temperature. This mild protocol displays broad substrate scope, good functional group tolerance and the catalyst can be easily isolated and reused for several cycles. It thereby addresses the two major limitations of previously reported photoredox-mediated Minisci reactions: (i) use of expensive and potentially harmful non-recyclable photocatalysts, and (ii) requirement of a stoichiometric amount of strong chemical oxidant. Finally, using platinum as a co-catalyst with the carbon nitride allows this light-mediated reaction to generate two value-added products under an anaerobic atmosphere – functionalised heteroarenes and H2 fuel.
Photocatalytic conversion of CO2 into carbonaceous feedstock chemicals is a promising strategy to mitigate greenhouse gas emissions and simultaneously store solar energy in chemical form. ...Photocatalysts for this transformation are typically based on precious metals and operate in nonaqueous solvents to suppress competing H2 generation. In this work, we demonstrate selective visible-light-driven CO2 reduction in water using a synthetic photocatalyst system that is entirely free of precious metals. We present a series of self-assembled nickel terpyridine complexes as electrocatalysts for the reduction of CO2 to CO in organic media. Immobilization on CdS quantum dots allows these catalysts to be active in purely aqueous solution and photocatalytically reduce CO2 with >90% selectivity under UV-filtered simulated solar light irradiation (AM 1.5G, 100 mW cm–2, λ > 400 nm, pH 6.7, 25 °C). Correlation between catalyst immobilization efficiency and product selectivity shows that anchoring the molecular catalyst on the semiconductor surface is key in controlling the selectivity for CO2 reduction over H2 evolution in aqueous solution.
Immobilization of a phosphonated cobalt bis(terpyridine) catalyst on TiO2 nanoparticles generates a photocatalyst that allows coupling aqueous CO2‐to‐syngas (CO and H2) reduction to selective ...oxidation of biomass‐derived oxygenates or cellulose to formate. An enzymatic saccharification pre‐treatment process is employed that enables the use of insoluble cellulose as an electron‐donating substrate under benign aqueous conditions suitable for photocatalytic CO2 conversion. The hybrid photocatalyst consists of solely earth‐abundant components, and its heterogeneous nature allows for reuse and operation in aqueous solution for several days at 25 °C, reaching a cellulose‐to‐formate conversion yield of 17 %. Thus, the proof‐of‐concept for valorizing two waste streams (CO2 and biomass) simultaneously into value‐added chemicals through solar‐driven catalysis is demonstrated.
A hybrid photocatalyst consisting of a phosphonated cobalt bis(terpyridine) catalyst immobilized on TiO2 powder allows coupling of aqueous CO2‐to‐syngas (CO and H2) reduction with the selective oxidation of biomass‐derived oxygenates or cellulose to formate. Thus, the simultaneous conversion of two waste streams into sustainable chemicals using sunlight is demonstrated.
PDF
