Photoinduced electron transfer pathways in hydrogen-evolving reduced graphene oxide-boosted hybrid nano-bio catalyst

Space-confined mediation of electron transfer for efficient biomolecular solar conversion

Solar-converting nanosystems using self-renewing biomaterial resources carry great potential for developing sustainable technologies to ameliorate climate change and minimize reliance on fossil fuels. By mimicking natural photosynthesis, diverse proof-of-concept biosolar systems have been used to produce green electricity, fuels and chemicals. Efforts so far have focused on optimizing light harvesting, biocatalyst loading and electron transfer (ET), however, the long-term performance of best-performing systems remains a major challenge due to the intensive use of diffusive, toxic mediators. To overcome this limitation, we developed a rationally designed nanosystem based on the entrapment of non-toxic mediator, ferrocene dimethanol (Fc), localized at the abiotic-biotic molecular interface that efficiently promoted ET between electrode surface and two photosynthetic proteins: cytochrome c and photosystem I. We demonstrate that space-confined Fc mediators (1 nM) are as effective in terms of ET kinetics as a 500 000-fold higher concentration of freely-diffusive Fc. The Fc-confined biophotocathodes showed a milestone photocurrent density of 14 μA cm-2 under oxic conditions compared to analogous planar (2D) biophotoelectrodes, with a photoconductive biolayer stable for over 5 months. The space-confined ET mediation reported in this work opens a new avenue for efficiently interfacing biomachineries, providing a benchmark design advancement in the quest for viable biohybrid technologies.

Revisiting Solar Energy Flow in Nanomaterial-Microorganism Hybrid Systems

Nanomaterial-microorganism hybrid systems (NMHSs), integrating semiconductor nanomaterials with microorganisms, present a promising platform for broadband solar energy harvesting, high-efficiency carbon reduction, and sustainable chemical production. While studies underscore its potential in diverse solar-to-chemical energy conversions, prevailing NMHSs grapple with suboptimal energy conversion efficiency. Such limitations stem predominantly from an insufficient systematic exploration of the mechanisms dictating solar energy flow. This review provides a systematic overview of the notable advancements in this nascent field, with a particular focus on the discussion of three pivotal steps of energy flow: solar energy capture, cross-membrane energy transport, and energy conversion into chemicals. While key challenges faced in each stage are independently identified and discussed, viable solutions are correspondingly postulated. In view of the interplay of the three steps in affecting the overall efficiency of solar-to-chemical energy conversion, subsequent discussions thus take an integrative and systematic viewpoint to comprehend, analyze and improve the solar energy flow in the current NMHSs of different configurations, and highlighting the contemporary techniques that can be employed to investigate various aspects of energy flow within NMHSs. Finally, a concluding section summarizes opportunities for future research, providing a roadmap for the continued development and optimization of NMHSs.

Bioinspired Light-Driven Proton Pump: Engineering Band Alignment of WS2 with PEDOT:PSS and PDINN

Bioinspired two-dimensional (2D) nanofluidic systems for photo-induced ion transport have attracted great attention, as they open a new pathway to enabling light-to-ionic energy conversion. However, there is still a great challenge in achieving a satisfactory performance. It is noticed that organic solar cells (OSCs, light-harvesting device based on photovoltaic effect) commonly require hole/electron transport layer materials (TLMs), PEDOT:PSS (PE) and PDINN (PD), respectively, to promote the energy conversion. Inspired by such a strategy, an artificial proton pump by coupling a nanofluidic system with TLMs is proposed, in which the PE- and PD-functionalized tungsten disulfide (WS2) multilayers construct a heterogeneous membrane, realizing an excellent output power of ≈1.13 nW. The proton transport is fine-regulated due to the TLMs-engineered band structure of WS2. Clearly, the incorporating TLMs of OSCs into 2D nanofluidic systems offers a feasible and promising approach for band edge engineering and promoting the light-to-ionic energy conversion.

Glycol 400 assisted preparation of high contact surface TiO2/GO nanocomposites for photocatalytic degradation rhodamine B

TiO2/graphene oxide (GO) nanocomposites with high contact interface were prepared with glycol 400 (PEG400) served as dispersant. This nanocomposite exhibits improved photocatalytic efficiency in contrast with the nanocomposite prepared without PEG400. In this work, the photocatalytic performance was investigated by observing the degradation rate of Rhodamine B (RhB). And it is found that the mass ratios of GO in nanocomposites plays an important role. When the mass ratio of GO reached 45%, the photocatalytic performance of the nanocomposites reached the highest, which is ∼72%. Moreover, the photocatalytic mechanism was studied through theoretical calculations, which can be summarized as follows: (1) the presence of GO decreases the band gap of TiO2nanoparticles. (2) GO inhibits the the recombination of photogenerated electron-hole pair. (3) GO improves the adsorption capacity of TiO2nanoparticles for RhB. This work promoted the application of TiO2/GO nanocomposites in wastewater treatment.

Nanoparticle Self-Assembly: From Design Principles to Complex Matter to Functional Materials

The creation of matter with varying degrees of complexities and desired functions is one of the ultimate targets of self-assembly. The ability to regulate the complex interactions between the individual components is essential in achieving this target. In this direction, the initial success of controlling the pathways and final thermodynamic states of a self-assembly process is promising. Despite the progress made in the field, there has been a growing interest in pushing the limits of self-assembly processes. The main inception of this interest is that the intended self-assembled state, with varying complexities, may not be "at equilibrium (or at global minimum)", rendering free energy minimization unsuitable to form the desired product. Thus, we believe that a thorough understanding of the design principles as well as the ability to predict the outcome of a self-assembly process is essential to form a collection of the next generation of complex matter. The present review highlights the potent role of finely tuned interparticle interactions in nanomaterials to achieve the preferred self-assembled structures with the desired properties. We believe that bringing the design and prediction to nanoparticle self-assembly processes will have a similar effect as retrosynthesis had on the logic of chemical synthesis. Along with the guiding principles, the review gives a summary of the different types of products created from nanoparticle assemblies and the functional properties emerging from them. Finally, we highlight the reasonable expectations from the field and the challenges lying ahead in the creation of complex and evolvable matter.

An Insight into Carbon Nanomaterial-Based Photocatalytic Water Splitting for Green Hydrogen Production

At present, the energy shortage and environmental pollution are the burning global issues. For centuries, fossil fuels have been used to meet worldwide energy demand. However, thousands of tons of greenhouse gases are released into the atmosphere when fossil fuels are burned, contributing to global warming. Therefore, green energy must replace fossil fuels, and hydrogen is a prime choice. Photocatalytic water splitting (PWS) under solar irradiation could address energy and environmental problems. In the past decade, solar photocatalysts have been used to manufacture sustainable fuels. Scientists are working to synthesize a reliable, affordable, and light-efficient photocatalyst. Developing efficient photocatalysts for water redox reactions in suspension is a key to solar energy conversion. Semiconductor nanoparticles can be used as photocatalysts to accelerate redox reactions to generate chemical fuel or electricity. Carbon materials are substantial photocatalysts for total WS under solar irradiation due to their high activity, high stability, low cost, easy production, and structural diversity. Carbon-based materials such as graphene, graphene oxide, graphitic carbon nitride, fullerenes, carbon nanotubes, and carbon quantum dots can be used as semiconductors, photosensitizers, cocatalysts, and support materials. This review comprehensively explains how carbon-based composite materials function as photocatalytic semiconductors for hydrogen production, the water-splitting mechanism, and the chemistry of redox reactions. Also, how heteroatom doping, defects and surface functionalities, etc., can influence the efficiency of carbon photocatalysts in H2 production. The challenges faced in the PWS process and future prospects are briefly discussed.

Synthesis, modification and application of titanium dioxide nanoparticles: a review

Titanium dioxide (TiO₂) has been heavily investigated owing to its low cost, benign nature and strong photocatalytic ability. Thus, TiO₂ has broad applications including photocatalysts, Li-ion batteries, solar cells, medical research and so on. However, the performance of TiO₂ is not satisfactory due to many factors such as the broad band gap (3.01 to 3.2 eV) and fast recombination of electron-hole pairs (10^-12 to 10^-11 s). Plenty of work has been undertaken to improve the properties, such as structural and dopant modifications, which broaden the applications of TiO₂. This review mainly discusses the aspects of TiO₂-modified nanoparticles including synthetic methods, modifications and applications.

In-situ stabilization of silver nanoparticles in polymer hydrogels for enhanced catalytic reduction of macro and micro pollutants

The in-situ stabilization of Ag nanoparticles is carried out by the use of reducing agent and synthesized three different types of hydrogen (anionic, cationic, and neutral) template. The morphology, constitution and thermal stability of the synthesized pure and Ag-entrapped hybrid hydrogels were efficiently confirmed using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and thermo gravimetric analysis (TGA). The prepared hybrid hydrogels were used in the decolorization of methylene blue (MB) and azo dyes congo red (CR), methyl Orange (MO), and reduction of 4-nitrophenol (4-NP) and nitrobenzene (NB) by an electron donor NaBH4. The kinetics of the reduction reaction was also assessed to determine the activation parameters. The hybrid hydrogen catalysts were recovered by filtration and used continuously up to six times with 98% conversion of pollutants without substantial loss in catalytic activity. It was observed that these types of hydrogel systems can be used for the conversion of pollutants from waste water into useful products.

Photocatalytic activity of exfoliated graphite-TiO2 nanoparticle composites

We investigate the photocatalytic performance of composites prepared in a one-step process by liquid-phase exfoliation of graphite in the presence of TiO₂ nanoparticles (NPs) at atmospheric pressure and in water, without heating or adding any surfactant, and starting from low-cost commercial reagents. These show enhanced photocatalytic activity, degrading up to 40% more pollutants with respect to the starting TiO₂-NPs, in the case of a model dye target, and up to 70% more pollutants in the case of nitrogen oxides. In order to understand the photo-physical mechanisms underlying this enhancement, we investigate the photo-generation of reactive species (trapped holes and electrons) by ultrafast transient absorption spectroscopy. We observe an electron transfer process from TiO₂ to the graphite flakes within the first picoseconds of the relaxation dynamics, which causes the decrease of the charge recombination rate, and increases the efficiency of the reactive species photo-production.

Enhanced CO2 reduction and valuable C2+ chemical production by a CdS-photosynthetic hybrid system

Semi-artificial photosynthesis is an emerging technique in recent years. Here, we presented an inorganic-biological hybrid system composed of photosynthetic Rhodopseudomonas palustris and CdS nanoparticles coated on the bacterial surface. Under visible light irradiation, the CO2 reduction and valuable C2+ chemical production of R. palustris could be promoted by the photo-induced electrons from the CdS NPs. The increased energy-rich NADPH cofactor promoted the generation of the Calvin cycle intermediate, glyceraldehyde-3-phosphate. As a result, the production of solid biomass, carotenoids and poly-β-hydroxybutyrate (PHB) was increased to 148%, 122% and 147%, respectively. The photosynthetic efficiency (PE) of CdS-R. palustris was elevated from the original 4.31% to 5.98%. The surface loaded NP amount and the material-cell interface both played important roles in the efficient electron generation and transduction. The CdS-R. palustris hybrid system also exhibited a survival advantage over its natural counterparts under the autotrophic conditions. Under a practical solar/dark cycle, the produced biomass, carotenoid and PHB from the hybrid system also reach 139%, 117% and 135%, respectively. The CdS-photosynthetic hybrid system represents a powerful and expandable platform for advanced CO2 reduction and solar-to-chemical (S2C) conversion.

Enhanced catalytic activity of nanosilver with lignin/polyacrylamide hydrogel for reducing p-nitrophenol

Lignin, as the second largest natural polymer in nature, has great practical application value. Three-dimensional silver/lignin/PAM hydrogels have been successfully prepared via a rapid and convenient assembly process, showing good catalytic hydrogenation ability and stability in batch and dynamic catalytic processes of p-nitrophenol. It can be seen from the characterization results that abundant amino groups in the catalyst carrier can disperse silver ions homogeneously and limit the growth of silver nanoparticles in the reduction process with sodium borohydride. At room temperature, the catalytic process can be completed in about 5 min by using this catalyst and can maintain about 100 min of efficient catalysis in the dynamic catalytic experiment, the conversion rate can reach about 80%. After 10 times use, the catalyst still maintained good catalytic performance and the conversion rate could be kept at 97%.

Strategies to improve the photocatalytic activity of TiO2: 3D nanostructuring and heterostructuring with graphitic carbon nanomaterials

TiO2-based photocatalysis has been considered to be one of the most promising avenues for environmental remediation including water purification. However, several technical issues such as the limited surface area of bulk TiO2, the large band gap of TiO2, and rapid charge recombination still limit the practical application of TiO2 photocatalysts. Therefore, here we focus on two structural design strategies: (i) monolithic three-dimensional (3D) nanostructuring, and (ii) heterostructuring with graphitic carbon nanomaterials. A monolithic 3D nanostructure enables maximal surface area in a given volume and efficient reuse of the photocatalyst without recollection. Heterostructuring with carbon nanomaterials helps achieve maximal utilization of the solar spectrum and charge separation and provides efficient TiO2 photocatalysts. In this review, recent progress on TiO2 photocatalysts toward the abovementioned strategies will be summarized. Further discussion and direction will provide insights into the rational design of highly efficient TiO2 photocatalysts, and help develop advanced photocatalyst models.

Composite of CH3 NH3 PbI3 with Reduced Graphene Oxide as a Highly Efficient and Stable Visible-Light Photocatalyst for Hydrogen Evolution in Aqueous HI Solution

A facile and efficient photoreduction method is employed to synthesize the composite of methylammonium lead iodide perovskite (MAPbI₃ ) with reduced graphene oxide (rGO). This MAPbI₃ /rGO composite is shown to be an outstanding visible-light photocatalyst for H₂ evolution in aqueous HI solution saturated with MAPbI₃ . Powder samples of MAPbI₃ /rGO (100 mg) show a H₂ evolution rate of 93.9 µmol h^-1 , which is 67 times faster than that of pristine MAPbI₃ , under 120 mW cm^-2 visible-light (λ ≥ 420 nm) illumination, and the composite is highly stable showing no significant decrease in the catalytic activity after 200 h (i.e., 20 cycles) of repeated H₂ evolution experiments. The electrochemiluminescence performance of MAPbI₃ is investigated to explore the charge transfer process, to find that the photogenerated electrons in MAPbI₃ are transferred to the rGO sites, where protons are reduced to H₂ .

Detergent-resistant oligomeric Leptosphaeria rhodopsin is a promising bio-nanomaterial and an alternative to bacteriorhodopsin

Bacteriorhodopsin has attracted remarkable attention as a photoactive bio-nanomaterial in the last decades. However, its instability in the presence of detergents has restricted the extent to which bacteriorhodopsin may be applied. In this study, we investigated the oligomerization of a eukaryotic light-driven H⁺-pump, Leptosphaeria rhodopsin, using circular dichroism spectroscopy and other biophysical and biochemical methods. Our findings revealed that Leptosphaeria rhodopsin assembled into oligomers in the cell membrane and also in 0.05% DDM detergent micelles. Moreover, unlike bacteriorhodopsin in purple membrane, Leptosphaeria rhodopsin retained its oligomeric structure in 1% Triton X-100 and demonstrated strong resistance to other common detergents. A maximal photocurrent density of ∼85 nA/cm² was consistently generated, which was substantially larger than that of solubilized bacteriorhodopsin (∼10 nA/cm²). Therefore, oligomeric Leptosphaeria rhodopsin may be a promising bio-nanomaterial, and an alternative to bacteriorhodopsin, especially with the use of detergents.

Probing photoinduced electron-transfer in graphene-dye hybrid materials for DSSC

We investigated the photophysical properties of a newly synthesized hybrid material composed of a triphenylamine dye covalently bound to reduced graphene oxide, potentially relevant as a stable photosensitizer in dye-sensitized solar cells. The photophysical characterization has been carried out by means of fluorescence quenching and fluorescence lifetime measurements, complemented by Electron Paramagnetic Resonance (EPR) spectroscopy, aimed at the detailed description of the photoinduced processes occurring in the hybrid and in the mixed hybrid/N-doped TiO₂ material. The combined optical/magnetic study unequivocally demonstrates a fast quenching of the dye excited state in the isolated hybrid and an efficient electron transfer to N-doped titania nanopowders. In the latter case, a metastable radical cation on the dye moiety is photogenerated and the corresponding negative charge, an electron, is trapped in defect sites of the doped semiconductor oxide. The spin distribution in the stable radical has been determined by EPR spectroscopy and correlated with DFT calculations.

Carbon-Based Nanobiohybrid Thin Film for Amperometric Glucose Sensing

This pioneering study involved the fabrication of a new class of nanohybrid-based electrochemical glucose biosensor. First, three-dimensional (3D) graphene was fabricated as a platform of multiwalled carbon nanotube (MWCNT). Then, it was used to immobilize glucose oxidase (GOD) on nanohybrid thin film via the entrapment technique. The modified glucose biosensor indicated excellent biocatalytic activity toward the glucose measurment with a sensitivity of up to 49.58 μA mM^-1 cm^-2 and a wide linear dynamic range up to 16 mM. The fabricated biosensor shows an excellent stability of 87.8%, with its current diminishing after 3 months. This facile and simple electrochemical method for glucose monitoring using a modified glassy carbon electrode (GCE) by 3DG-MWCNT-GOD could open new avenues in producing of a inexpensive and sensitive glucose nanobiosensors.

Cell-Free Synthetic Biology Chassis for Nanocatalytic Photon-to-Hydrogen Conversion

We report on an entirely man-made nano-bio architecture fabricated through noncovalent assembly of a cell-free expressed transmembrane proton pump and TiO₂ semiconductor nanoparticles as an efficient nanophotocatalyst for H₂ evolution. The system produces hydrogen at a turnover of about 240 μmol of H₂ (μmol protein)^-1 h^-1 and 17.74 mmol of H₂ (μmol protein)^-1 h^-1 under monochromatic green and white light, respectively, at ambient conditions, in water at neutral pH and room temperature, with methanol as a sacrificial electron donor. Robustness and flexibility of this approach allow for systemic manipulation at the nanoparticle-bio interface toward directed evolution of energy transformation materials and artificial systems.

Nano-Photoelectrochemical Cell Arrays with Spatially Isolated Oxidation and Reduction Channels

Photoelectrochemical conversion of solar energy is explored for many diverse applications but suffers from poor efficiencies due to limited solar absorption, inadequate charge carrier separation, redox half-reactions occurring in close proximity, and/or long ion diffusion lengths. We have taken a drastically different approach to the design of photoelectrochemical cells (PECs) to spatially isolate reaction sites at the nanoscale to different materials and flow channels, suppressing carrier recombination and back-reaction of intermediates while shortening ion diffusion paths and, importantly, avoiding mixed product generation. We developed massively parallel nano-PECs composed of an array of open-ended carbon nanotubes (CNTs) with photoanodic reactions occurring on the outer walls, uniformly coated with titanium dioxide (TiO₂), and photocathodic reactions occurring on the inner walls, decorated with platinum (Pt). We verified the redox reaction isolation by demonstrating selective photodeposition of manganese oxide on the outside and silver on the inside of the TiO₂/CNT/Pt nanotubes. Further, the nano-PECs exhibit improved solar absorption and efficient charge transfer of photogenerated carriers to their respective redox sites, leading to a 1.8% photon-to-current conversion efficiency (a current density of 4.2 mA/cm²) under white-light irradiation. The design principles demonstrated can be readily adapted to myriads of photocatalysts for cost-effective solar utilization.

Protein-directed assembly of cobalt phosphate hybrid nanoflowers

The understanding and controlling of biomimetic hybrid materials are a key objective in bio-nanotechnology, materials chemistry, and colloid science fields. Biomaterials, such as, enzyme, DNA, RNA, and proteins have become important templates for the construction of inorganic-organic hybrid nanoflowers. From this perspective, we present a simple approach to synthesize protein and metal hybrid flower-like structure using bovine serum albumin (BSA) and cobalt phosphate, and the results of our study on the formation mechanism involved. The time dependent growing stage and formation mechanism were analyzed by electron microscopes and spectroscopic techniques. The protein-directed assembly method for preparation of hybrid nanoflowers described in this work could be used to fabricate other bio-metal hybrid materials with possible applications in biosensors, bioanalytical devices, and industrial biocatalyst fields.

Photocatalytic conversion of CO2 over graphene-based composites: current status and future perspective

The continuous rise in the atmospheric CO₂ level and the ever-increasing demand of energy have raised serious concerns about the ensuing effects on the global climate change and future energy supply. Photocatalytic conversion of CO₂, which uses solar light energy to recycle CO₂ into fuels and chemicals, provides a promising and straightforward strategy to simultaneously reduce the atmospheric CO₂ level and fulfil the future energy demand. However, the lack of substantial development of state-of-the-art materials remains a major bottleneck of this technology. In recent years, graphene-based composite photocatalysts have gained increasing interest in CO₂ conversion due to the introduction of graphene with a series of unique physicochemical properties, which has shown to play a significant role in promoting the photocatalytic solar energy conversion efficiency. In this review, we comprehensively summarize the typical literature reports on graphene-based composites for photocatalytic conversion of CO₂ to produce solar fuels and chemicals. The main types of the reported graphene-based composites and the role of graphene in the composites in improving the photocatalytic performance have been elaborated. In particular, we have highlighted the possible role of graphene in tuning the product selectivity of photocatalytic reduction of CO₂. Finally, perspectives on the existing problems and future research on graphene-based composites toward photocatalytic conversion of CO₂ are critically discussed.

Laccase-Functionalized Graphene Oxide Assemblies as Efficient Nanobiocatalysts for Oxidation Reactions

Multi-layer graphene oxide-enzyme nanoassemblies were prepared through the multi-point covalent immobilization of laccase from Trametes versicolor (TvL) on functionalized graphene oxide (fGO). The catalytic properties of the fGO-TvL nanoassemblies were found to depend on the number of the graphene oxide-enzyme layers present in the nanostructure. The fGO-TvL nanoassemblies exhibit an enhanced thermal stability at 60 °C, as demonstrated by a 4.7-fold higher activity as compared to the free enzyme. The multi-layer graphene oxide-enzyme nanoassemblies can efficiently catalyze the oxidation of anthracene, as well as the decolorization of an industrial dye, pinacyanol chloride. These materials retained almost completely their decolorization activity after five reaction cycles, proving their potential as efficient nano- biocatalysts for various applications.

Laser-induced fabrication of highly branched Au@TiO2 nano-dendrites with excellent near-infrared absorption properties

The highly branched Au@TiO₂ nano-dendrites with excellent near-infrared absorption properties have been conveniently fabricated via a novel and effective laser-induced strategy.

Bio-nano hybrid materials based on bacteriorhodopsin: Potential applications and future strategies

This review presents an overview of recent progress in the development of bio-nano hybrid materials based on the photoactive protein bacteriorhodopsin (bR). The interfacing of bR with various nanostructures including colloidal nanoparticles (such as quantum dots and Ag NPs) and nanoparticulate thin films (such as TiO2 NPs and ZnO NPs,) has developed novel functional materials. Applications of these materials are comprehensively reviewed in two parts: bioelectronics and solar energy conversion. Finally, some perspectives on possible future strategies in bR-based nanostructured devices are presented.

Influence of electron storing, transferring and shuttling assets of reduced graphene oxide at the interfacial copper doped TiO2 p-n heterojunction for increased hydrogen production

Herein we report simple, low-cost and scalable preparation of reduced graphene oxide (rGO) supported surfactant-free Cu2O-TiO2 nanocomposite photocatalysts by an ultrasound assisted wet impregnation method. Unlike the conventional preparation techniques, simultaneous reduction of Cu(2+) (in the precursor) to Cu(+) (Cu2O), and graphene oxide (GO) to rGO is achieved by an ultrasonic method without the addition of any external reducing agent; this is ascertained by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses. UV-visible diffused reflectance spectroscopy (DRS) studies (Tauc plots) provide evidence for the loading of Cu2O tailoring the optical band gap of the photocatalyst from 3.21 eV to 2.87 eV. The photoreactivity of the as-prepared Cu2O-TiO2/rGO samples is determined via H2 evolution from water in the presence of glycerol as a hole (h(+)) scavenger under visible light irradiation. Very interestingly, the addition of rGO augments the carrier mobility at the Cu2O-TiO2 p-n heterojunction, which is evidenced by the significantly reduced luminescence intensity of the Cu2O-TiO2/rGO photocatalyst. Hence rGO astonishingly enhances the photocatalytic activity compared with pristine TiO2 nanoparticles (NPs) and Cu2O-TiO2, by factors of ∼14 and ∼7, respectively. A maximum H2 production rate of 110 968 μmol h(-1) gcat(-1) is obtained with a 1.0% Cu and 3.0% GO photocatalyst composition; this is significantly higher than previously reported graphene based photocatalysts. Additionally, the present H2 production rate is much higher than those of precious/noble metal (especially Pt) assisted (as co-catalysts) graphene based photocatalysts. Moreover, to the best of our knowledge, this is the highest H2 production rate (110 968 μmol h(-1) gcat(-1)) achieved by a graphene based photocatalyst through the splitting of water under visible light irradiation.

Visible light switchable bR/TiO 2 nanostructured photoanodes for bio-inspired solar energy conversion

Bacteriorhodopsin, a visible light sensitizer for the water splitting reaction, adsorbed on TiO ₂ nanoparticulate photoanode without any linker and caused a significant PEC enhancement.