In this work, the selective electrocatalytic reduction of carbon dioxide to carbon monoxide on oxide-derived silver electrocatalysts is presented. By a simple synthesis technique, the overall high faradaic efficiency for CO production on the oxide-derived Ag was shifted by more than 400 mV towards a lower overpotential compared to that of untreated Ag. Notably, the Ag resulting from Ag oxide is capable of electrochemically reducing CO2 to CO with approximately 80 % catalytic selectivity at a moderate overpotential of 0.49 V, which is much higher than that (ca. 4 %) of untreated Ag under identical conditions. Electrokinetic studies show that the improved catalytic activity is ascribed to the enhanced stabilization of COOH(.) intermediate. Furthermore, highly nanostructured Ag is likely able to create a high local pH near the catalyst surface, which may also facilitate the catalytic activity for the reduction of CO2 with suppressed H2 evolution.

Cyanobacteriochromes are phytochrome homologues in cyanobacteria that act as sensory photoreceptors. We compare two cyanobacteriochromes, RGS (coded by slr1393) from Synechocystis sp. PCC 6803 and AphC (coded by all2699) from Nostoc sp. PCC 7120. Both contain three GAF (cGMP phosphodiesterase, adenylyl cyclase and FhlA protein) domains (GAF1, GAF2 and GAF3). The respective full-length, truncated and cysteine point-mutated genes were expressed in Escherichia coli together with genes for chromophore biosynthesis. The resulting chromoproteins were analyzed by UV-visible absorption, fluorescence and circular dichroism spectroscopy as well as by mass spectrometry. RGS shows a red-green photochromism (k max = 650 and 535 nm) that is assigned to the reversible 15Z ⁄ E isomerization of a single phycocyanobilin-chromophore (PCB) binding to Cys528 of GAF3. Of the three GAF domains, only GAF3 binds a chromophore and the binding is autocatalytic. RGS autophosphorylates in vitro; this reaction is photoregulated: the 535 nm state containing E-PCB was more active than the 650 nm state containing Z-PCB. AphC from Nostoc could be chromophorylated at two GAF domains, namely GAF1 and GAF3. PCB-GAF1 is photochromic, with the proposed 15E state (k max = 685 nm) reverting slowly thermally to the thermostable 15Z state (k max = 635 nm). PCB-GAF3 showed a novel red-orange photochromism; the unstable state (putative 15E, k max = 595 nm) reverts very rapidly (s 20 s) back to the thermostable Z state (k max = 645 nm). The photochemistry of doubly chromophorylated AphC is accordingly complex, as is the autophosphorylation: E-GAF1 ⁄ E-GAF3 shows the highest rate of autophosphorylation activity, while E-GAF1 ⁄ Z-GAF3 has intermediate activity, and Z-GAF1 ⁄ Z-GAF3 is the least active state. Structured digital abstractl AphC phosphorylates AphC by protein kinase assay (View interaction) l RGS phosphorylates RGS by protein kinase assay (View interaction) Abbreviations AphC, protein encoded by aphC = all2699; CBR, cyanobacteriochrome; GAF, cGMP phosphodiesterase, adenylyl cyclase and FhlA protein domain (SMART acc. no. SM00065); KPB, potassium phosphate buffer; Nostoc, Anabaena (Nostoc) sp. PCC 7120; P XXX ⁄ P YYY , the two photoconvertible states of CBR or Phy designated by the absorption maxima, with the stable generally 15Z state (k max = XXX nm) preceding the light-activated generally 15E-configured state (k max = YYY nm); PAS, period circadian protein, Ah receptor nuclear translocator protein and single-minded protein domain (SMART acc. no. SM00091); PCB, phycocyanobilin; Phy, phytochrome; PVB, phycoviolobilin; PFB, phytochromobilin; RGS, red-green switchable protein encoded by rgs = slr1393; Synechocystis, Synechocystis sp. PCC 6803.

In this work, the selective electrocatalytic reduction of carbon dioxide to carbon monoxide on oxide‐derived silver electrocatalysts is presented. By a simple synthesis technique, the overall high faradaic efficiency for CO production on the oxide‐derived Ag was shifted by more than 400 mV towards a lower overpotential compared to that of untreated Ag. Notably, the Ag resulting from Ag oxide is capable of electrochemically reducing CO2 to CO with approximately 80 % catalytic selectivity at a moderate overpotential of 0.49 V, which is much higher than that (ca. 4 %) of untreated Ag under identical conditions. Electrokinetic studies show that the improved catalytic activity is ascribed to the enhanced stabilization of COOH. intermediate. Furthermore, highly nanostructured Ag is likely able to create a high local pH near the catalyst surface, which may also facilitate the catalytic activity for the reduction of CO2 with suppressed H2 evolution.

Improving electrochemical properties of hydrothermally synthesized LiFePO(4) powders is of immense technological significance and has been a subject of much scientific inquiry for many years. As reported previously, reversing the feeding sequence of starting materials and/or introducing ethylene glycol (EG) could significantly improve the electrochemical performance of hydrothermally synthesized LiFePO(4). However, the mechanism remains unclear. Here, we report a systematic study to understand the mechanism from viewpoints of crystal growth and defect concentration control. Combining the results of experimental and theoretical investigations, the improvement in electrochemical performance is attributed to simultaneous suppression of crystal growth along the [010] direction and reduced defect concentration of the antisite. The reduction in antisite defects is readily monitored by significant red shift of the infrared (IR) absorption band around 1000 cm(-1) which is assigned to the symmetric stretching P-O vibration of the PO(4) tetrahedron, as indicated by theoretical calculation. With this knowledge in mind, an output as high as 450 g L(-1) (autoclave volume), and an enhanced specific discharge capacity of 165 A h kg(-1) (close to the theoretical unity of 170 A h kg(-1)) at 0.1 C are achieved.