Leading solar fuels research since 1994
 

Welcome!

The Swedish Consortium for Artificial Photosynthesis is a collaborative research environment with the purpose of advancing the science and utilization of solar fuels - fuel from solar energy. We bring together leading scientists with expertise in molecular biology, biophysics and biochemistry, synthetic chemistry and chemical physics.

The Consortium was started in 1994. Since then we have assembled the necessary expertise in an integrated research body, known as the Swedish Consortium for Artificial Photosynthesis.

Here we present who we are and what is going on in our research. We invite anyone who wants to know more about artificial photosynthesis and solar fuels to follow the links to the homepages of our researchers.  

Welcome!

News

July 16 2019:  Xufeng Liu,  Rui Miao,  Pia Lindberg  and  Peter Lindblad published an article in Energy & Environmental Science: 

Modular Engineering for Efficient Photosynthetic Biosynthesis of 1-Butanol from CO2 in Cyanobacteria

Abstract: Cyanobacteria are photoautotrophic microorganisms which can be engineered to directly convert CO2 and water into biofuels and chemicals via photosynthesis using sunlight as energy. However, product titers and rates are main challenges that need to be overcome for industrial applications. Here we present a systematic modular engineering of the cyanobacterium Synechocystis PCC 6803, enabling efficient biosynthesis of 1-butanol, an attractive commodity chemical and gasoline substitute. Through introducing and re-casting the 1-butanol biosynthetic pathway at gene and enzyme levels, optimizing the 5’-regions of expression units for tuning transcription and translation, rewiring carbon flux and rewriting the photosynthetic central carbon metabolism to enhance the precursor supply, and performing process development, we were able to reach a cumulative 1-butanol titer of 4.8 g∙L-1 with a maximal rate of 302 mg∙L-1∙day-1 from the engineered Synechocystis. This represents the highest 1-butanol production from CO2 reported so far. Our multi-level modular strategy for high-level production of chemicals and advanced biofuels represents a blue-print for future systematic engineering in photosynthetic microorganisms.

June 11 2019:  Jing Huang, Bo Xu, Lei Tian, Palas Baran Pati, Ahmed S. Etman, Junliang Sun, Leif Hammarström and Haining Tian published an article in Chemical Communications: 

A heavy metal-free CuInS2 quantum dot sensitized NiO photocathode with a Re molecular catalyst for photoelectrochemical CO2 reduction.

Abstract: Heavy metal-free CuInS2 quantum dots (QDs) were employed as a photosensitizer on a NiO photocathode to drive an immobilized molecular Re catalyst for photoelectrochemical CO2 reduction for the first time. A photocurrent of 25 μA cm−2 at −0.87 V vs. NHE was obtained, providing a faradaic efficiency of 32% for CO production.

May 2 2019:  Alexander Aster, Shihuai Wang, Mohammad Mirmohades, Charlène Esmieu, Gustav Berggren, Leif Hammarström and Reiner Lomoth published an article in Chemical Science: 

Metal vs. ligand protonation and the alleged proton-shuttling role of the azadithiolate ligand in catalytic H2 formation with FeFe hydrogenase model complexes.

Abstract: Electron and proton transfer reactions of diiron complexes [Fe2adt(CO)6] (1) and [Fe2adt(CO)4(PMe3)2] (4), with the biomimetic azadithiolate (adt) bridging ligand, have been investigated by real-time IR- and UV-vis-spectroscopic observation to elucidate the role of the adt-N as a potential proton shuttle in catalytic H2 formation. Protonation of the one-electron reduced complex, 1−, occurs on the adt-N yielding 1H and the same species is obtained by one-electron reduction of 1H+. The preference for ligand vs. metal protonation in the Fe2(I,0) state is presumably kinetic but no evidence for tautomerization of 1H to the hydride 1Hy was observed. This shows that the adt ligand does not work as a proton relay in the formation of hydride intermediates in the reduced catalyst. A hydride intermediate 1HHy+ is formed only by protonation of 1H with stronger acid. Adt protonation results in reduction of the catalyst at much less negative potential, but subsequent protonation of the metal centers is not slowed down, as would be expected according to the decrease in basicity. Thus, the adtH+ complex retains a high turnover frequency at the lowered overpotential. Instead of proton shuttling, we propose that this gain in catalytic performance compared to the propyldithiolate analogue might be rationalized in terms of lower reorganization energy for hydride formation with bulk acid upon adt protonation..

April 11 2019:  Giovanny A. Parada, Zachary K. Goldsmith, Scott Kolmar, Belinda Pettersson Rimgard, Brandon Q. Mercado, Leif Hammarström, Sharon Hammes-Schiffer, and James M. Mayer published an article in Science: 

Concerted proton-electron transfer reactions in the Marcus inverted region.

Abstract: Electron transfer (ET) reactions slow down when they become thermodynamically very favorable, a counterintuitive interplay of kinetics and thermodynamics termed the inverted region in Marcus theory. Here we report inverted region behavior for proton-coupled electron transfer (PCET). Specifically, photochemical studies of anthracene-phenol-pyridine triads give rate constants for PCET charge recombination that are slower for the more thermodynamically favorable reactions. Photoexcitation forms an anthracene excited state that undergoes PCET to create a charge separated state. The rate constants for return charge recombination show an inverted dependence on the driving force upon changing pyridine substituents and the solvent. Calculations using vibronically nonadiabatic PCET theory yield rate constants for simultaneous tunneling of the electron and proton that account for the results..

March 4, 2019: CAP scientists in the TV news

At the CAP meeting in Umeå, CAP researchers were discussing future hydrogen technology. We also had the chance to test drive a fuel cell vehicle that runs on hydrogen gas. Swedish public service television filmed the event, which can be watched here: Vätgasbilar spås ha nyckelroll i framtiden

February 21 2019:  Sonja Pullen, Somnath Maji, Matthias Stein and Sascha Ott published an article in Dalton transactions: 

Restricted rotation of an Fe(CO)2(PL3)-subunit in [FeFe]-hydrogenase active site mimics by intramolecular ligation.

Abstract: A new series of homodinuclear iron complexes as models of the [FeFe]-hydrogenase active site was prepared and characterized. The complexes of the general formula [Fe2(mcbdt)(CO)5PPh2R] (mcbdt = benzene-1,2-dithiol-3-carboxylic acid) feature covalent tethers that link the mcbdt ligand with the phosphine ligands which are terminally coordinated to one of the Fe centres. The synthetic feasability of the concept is demonstrated with the preparation of three novel complexes. A detailed theoretical investigation showes that by introducing a rigid covalent link between the phosphine and the bridging dithiolate ligands, the rotation of the Fe(CO)2P unit is hindered and higher rotation barriers were calculated compared to nonlinked reference complexes. The concept of restricting Fe(L)3 rotation is an approach to kinetically stabilize terminal hydrides which are reactive intermediates in catalytic proton reduction cycles of the enzymes.

February 18 2019:  Sergii I. Shylin, Mariia V. Pavliuk, Luca D’Amario, Fikret Mamedov, Jacinto Sá, Gustav Berggren and Igor O. Fritsky published an article in Chemical communications: 

Efficient visible light-driven water oxidation catalysed by an iron(IV) clathrochelate complex.

Abstract: A water-stable Fe(IV) clathrochelate complex catalyses fast and homogeneous photochemical oxidation of water to dioxygen with a turnover frequency of 2.27 /s and a maximum turnover number of 365. An Fe(V) intermediate generated under catalytic conditions is trapped and characterised using EPR and Mössbauer spectroscopy.


January 4 2019:  Kamonchanock Eungrasamee, Rui Miao, Aran Incharoensakdi, Peter Lindblad and Saowarath Jantaro published an article in Biotechnology for biofuels: 

Improved lipid production via fatty acid biosynthesis and free fatty acid recycling in engineered Synechocystis sp. PCC 6803.

Abstract: Cyanobacteria are potential sources for third generation biofuels. Their capacity for biofuel production has been widely improved using metabolically engineered strains. In this study, we employed metabolic engineering design with target genes involved in selected processes including the fatty acid synthesis (a cassette of accD, accA, accC and accB encoding acetyl-CoA carboxylase, ACC), phospholipid hydrolysis (lipA encoding lipase A), alkane synthesis (aar encoding acyl-ACP reductase, AAR), and recycling of free fatty acid (FFA) (aas encoding acyl–acyl carrier protein synthetase, AAS) in the unicellular cyanobacterium Synechocystis sp. PCC 6803.

January 3 2019:  Brigitta Németh, Charlène Esmieu,  Holly J. Redman and Gustav Berggren published an article in Dalton transactions: 

Monitoring H-cluster assembly using a semisynthetic HydF protein.

Abstract: The [FeFe] hydrogenase enzyme interconverts protons and molecular hydrogen with remarkable efficiency. The reaction is catalysed by a unique metallo-cofactor denoted as the H-cluster containing an organometallic dinuclear Fe component, the [2Fe] subsite. The HydF protein delivers a precursor of the [2Fe] subsite to the apo-[FeFe] hydrogenase, thus completing the H-cluster and activating the enzyme. Herein we generate a semi-synthetic form of HydF by loading it with a synthetic low valent dinuclear Fe complex. We show that this semi-synthetic protein is practically indistinguishable from the native protein, and utilize this form of HydF to explore the mechanism of H-cluster assembly. More specifically, we show that transfer of the precatalyst from HydF to the hydrogenase enzyme results in the release of CO, underscoring that the pre-catalyst is a four CO species when bound to HydF. Moreover, we propose that an electron transfer reaction occurs during H-cluster assembly, resulting in an oxidation of the [2Fe] subsite with concomitant reduction of the [4Fe4S] cluster present on the HydF protein. 


January 2019:  Bo Xu, Lei Tian, Ahmed S.Etman, Junliang Sun, and Haining Tian published an article in Nano energy:

Solution-processed nanoporous NiO-dye-ZnO photocathodes: Toward efficient and stable solid-state p-type dye-sensitized solar cells and dye-sensitized photoelectrosynthesis cells.

Abstract: A solution-processed NiO-dye-ZnO photocathode was developed for applications in both solid-state p-type dye-sensitized solar cells (p-ssDSCs) and p-type dye-sensitized photoelectrosynthesis cells (p-DSPECs). In p-ssDSCs, the solar cell using ZnO as electron transport material showed a short circuit current, up to 680 µA cm−2, which is 60-fold larger than that previously reported device using TiO2 as electron transport material with similar architecture. In the p-DSPECs, a remarkable photocurrent of 100 μA cm−2 was achieved in a pH = 5.0 acetate buffer solution under a bias potential at 0.05 V vs RHE with platinum as the proton reduction catalyst. A Faradaic efficiency approaching 100% for the H2 evolution reaction was obtained after photoelectrolysis for 9 h. Importantly, the solution-processed NiO-dye-ZnO photocathode exhibited excellent long-term stability in both p-ssDSCs and p-DSPECs. To the best of our knowledge, this is the first study where a solution-processable, nanoporous NiO-dye-ZnO photocathode is used for both p-ssDSCs and p-DSPECs having both excellent device performance and stability.



November 30, 2018: Kasper Skov Kjær, Nidhi Kaul, Om Prakash, Pavel Chábera, Nils W. Rosemann, Alireza Honarfar, Olga Gordivska, Lisa A. Fredin, Karl-Erik Bergquist, Lennart Häggström, Tore Ericsson, Linnea Lindh, Arkady Yartsev, Stenbjörn Styring, Ping Huang, Jens Uhlig, Jesper Bendix, Daniel Strand, Villy Sundström, Petter Persson, Reiner Lomoth, and Kenneth Wärnmark published an article in Science:

Luminescence and reactivity of a charge-transfer excited iron complex with nanosecond lifetime.

Abstract: 

Iron’s abundance and rich coordination chemistry are potentially appealing features for photochemical applications. However, the photoexcitable charge-transfer (CT) states of most Fe complexes are limited by picosecond or sub-picosecond deactivation through low-lying metal centered (MC) states, resulting in inefficient electron transfer reactivity and complete lack of photoluminescence. Here we show that octahedral coordination of Fe(III) by two mono-anionic facial tris-carbene ligands can suppress such deactivation dramatically. 

The resulting complex [Fe(phtmeimb)2]+, where phtmeimb is [phenyl(tris(3-methylimidazol-1-ylidene))borate]-, exhibits strong, visible, room temperature photoluminescence with a 2.0 ns lifetime and 2% quantum yield via spin-allowed transition from a ligand-to-metal charge-transfer (2LMCT) state to the ground state (2GS). Reductive and oxidative electron transfer reactions were observed for the 2LMCT state of [Fe(phtmeimb)2]+ in bimolecular quenching studies with methylviologen and diphenylamine.


Fig. 2Electrochemistry and spectroscopy of [Fe(phtmeimb)2]+ in dry acetonitrile at room temperature.

(A) Cyclic and differential pulse voltammetry. (B) Optical absorption (left black curve), normalized photoluminescence (right black) and normalized excitation spectra (red circles). (C) Visible orange photoluminescence of 50 μM [Fe(phtmeimb)2]+ in acetonitrile upon 532 nm excitation.


Participants in the CAP workshop in Sigtuna, Sweden, April 26-27, 2018.

Participants in the CAP workshop in Sigtuna, Sweden, April 26-27, 2018.


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Last updated July 29, 2019