Surface‐Plasmon‐Assisted Photoelectrochemical Reduction of CO2 and NO3− on Nanostructured Silver Electrodes

Electrochemical reduction of carbon dioxide (CO₂) typically suffers from low selectivity and poor reaction rates that necessitate high overpotentials, which impede its possible application for CO₂ capture, sequestration, or carbon‐based fuel production. New strategies to address these issues include the utilization of photoexcited charge carriers to overcome activation barriers for reactions that produce desirable products. This study demonstrates surface‐plasmon‐enhanced photoelectrochemical reduction of CO₂ and nitrate (NO₃^?) on silver nanostructured electrodes. The observed photocurrent likely originates from a resonant charge transfer between the photogenerated plasmonic hot electrons and the lowest unoccupied molecular orbital (MO) acceptor energy levels of adsorbed CO₂, NO₃^?, or their reductive intermediates. The observed differences in the resonant effects at the Ag electrode with respect to electrode potential and photon energy for CO₂ versus NO₃^? reduction suggest that plasmonic hot‐carriers interact selectively with specific MO acceptor energy levels of adsorbed surface species such as CO₂, NO₃^?, or their reductive intermediates. This unique plasmon‐assisted charge generation and transfer mechanism can be used to increase yield, efficiency, and selectivity of various photoelectrochemical processes.     

Activation of Ni Particles into Single Ni–N Atoms for Efficient Electrochemical Reduction of CO2

Electrochemical reduction of carbon dioxide (CO₂) to fuels and value‐added industrial chemicals is a promising strategy for keeping a healthy balance between energy supply and net carbon emissions. Here, the facile transformation of residual Ni particle catalysts in carbon nanotubes into thermally stable single Ni atoms with a possible NiN₃ moiety is reported, surrounded with a porous N‐doped carbon sheath through a one‐step nanoconfined pyrolysis strategy. These structural changes are confirmed by X‐ray absorption fine structure analysis and density functional theory (DFT) calculations. The dispersed Ni single atoms facilitate highly efficient electrocatalytic CO₂ reduction at low overpotentials to yield CO, providing a CO faradaic efficiency exceeding 90%, turnover frequency approaching 12 000 h^?1, and metal mass activity reaching about 10 600 mA mg^?1, outperforming current state‐of‐the‐art single atom catalysts for CO₂ reduction to CO. DFT calculations suggest that the Ni@N₃ (pyrrolic) site favors *COOH formation with lower free energy than Ni@N₄, in addition to exothermic CO desorption, hence enhancing electrocatalytic CO₂ conversion. This finding provides a simple, scalable, and promising route for the preparation of low‐cost, abundant, and highly active single atom catalysts, benefiting future practical CO₂ electrolysis.     

Determination of bergenin based on the electrochemiluminescence quenching of tris(2,2′‐bipyridine)‐ruthenium(II)

Quenching effects of bergenin, based on the electrochemiluminescence (ECL) of the tris(2,2′‐bipyridyl)‐ruthenium(II) (Ru(bpy)₃²⁺)/tri‐n‐propylamine (TPrA) system in aqueous solution, is been described. The quenching behavior can be observed with a 100‐fold excess of bergenin over Ru(bpy)₃²⁺. In the presence of 0.1 m TPrA, the Stern–Volmer constant (K_SV) of the ECL quenching is as high as 1.16 × 10⁴ M^?1 for bergenin. The logarithmic plot of the inhibited ECL versus logarithmic plot of the concentration of bergenin was linear over the range 3.0 × 10^?6–1.0 × 10^?4 mol/L. The corresponding limit of detection was 6.0 × 10^?7 mol/L for bergenin (S/N = 3). In the mechanism of quenching it is believed that the competition of the active free radicals between Ru(bpy)₃²⁺/TPrA and bergenin was the key factor for the ECL inhibition of the system. Photoluminescence, cyclic voltammetry, coupled with bulk electrolysis, supports the supposition mechanism of the Ru(bpy)₃²⁺/TPrA–bergenin system. Copyright © 2015 John Wiley & Sons, Ltd.     

Electrocatalytic Reduction of Gaseous CO2 to CO on Sn/Cu‐Nanofiber‐Based Gas Diffusion Electrodes

Earth‐abundant Sn/Cu catalysts are highly selective for the electrocatalytic reduction of CO₂ to CO in aqueous electrolytes. However, CO₂ mass transport limitations, resulting from the low solubility of CO₂ in water, so far limit the CO partial current density for Sn/Cu catalysts to about 10 mA cm^?2. Here, a freestanding gas diffusion electrode design based on Sn‐decorated Cu‐coated electrospun polyvinylidene fluoride nanofibers is demonstrated. The use of gaseous CO₂ as a feedstock alleviates mass transport limitations, resulting in high CO partial current densities above 100 mA cm^?2, while maintaining high CO faradaic efficiencies above 80%. These results represent an important step toward an economically viable pathway to CO₂ reduction.     

A Monodisperse Rh2P‐Based Electrocatalyst for Highly Efficient and pH‐Universal Hydrogen Evolution Reaction

The search for Pt‐free electrocatalysts exceeding pH‐universal hydrogen evolution reaction (HER) activities when compared to the state‐of‐the‐art commercial Pt/C is highly desirable for the development of renewable energy conversion systems but still remains a huge challenge. Here a colloidal synthesis of monodisperse Rh₂P nanoparticles with an average size of 2.8 nm and their superior catalytic activities for pH‐universal HER are reported. Significantly, the Rh₂P catalyst displays remarkable HER performance with overpotentials of 14, 30, and 38 mV to achieve 10 mA cm^?2 in 0.5 m H₂SO₄, 1.0 m KOH, and 1.0 m phosphate‐buffered saline, respectively, exceeding almost all the documented electrocatalysts, including the commercial 20 wt% Pt/C. Density functional theory calculations reveal that the introduction of P into Rh can weaken the H adsorption strength of Rh₂P to nearly zero, beneficial for boosting HER performance.     

Continuous 3D Titanium Nitride Nanoshell Structure for Solar‐Driven Unbiased Biocatalytic CO2 Reduction

Z‐scheme‐inspired tandem photoelectrochemical (PEC) cells have received attention as a sustainable platform for solar‐driven CO₂ reduction. Here, continuously 3D‐structured, electrically conductive titanium nitride nanoshells (3D TiN) for biocatalytic CO₂‐to‐formate conversion in a bias‐free tandem PEC system are reported. The 3D TiN exhibits a periodically porous network with high porosity (92.1%) and conductivity (6.72 × 10⁴ S m^?1), which allows for high enzyme loading and direct electron transfer (DET) to the immobilized enzyme. It is found that the W‐containing formate dehydrogenase from Clostridium ljungdahlii (ClFDH) on the 3D TiN nanoshell is electrically activated through DET for CO₂ reduction. At a low overpotential of 40 mV, the 3D TiN‐ClFDH stably converts CO₂ to formate at a rate of 0.34 µmol h^?1 cm^?2 and a faradaic efficiency (FE) of 93.5%. Compared to a flat TiN‐ClFDH, the 3D TiN‐ClFDH shows a 58 times higher formate production rate (1.74 µmol h^?1 cm^?2) at 240 mV of overpotential. Lastly, a bias‐free biocatalytic tandem PEC cell that converted CO₂ to formate at an average rate of 0.78 µmol h^?1 and an FE of 77.3% only using solar energy and water is successfully assembled.     

Ultralow Ru Loading Transition Metal Phosphides as High‐Efficient Bifunctional Electrocatalyst for a Solar‐to‐Hydrogen Generation System

Water splitting is a promising technology for sustainable conversion of hydrogen energy. The rational design of oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) bifunctional electrocatalysts with superior activity and stability in the same electrolyte is the key to promoting their large‐scale applications. Herein, an ultralow Ru (1.08 wt%) transition metal phosphide on nickel foam (Ru–MnFeP/NF) derived from Prussian blue analogue, that effectively drivies both the OER and the HER in 1 m KOH, is reported. To reach 20 mA cm^?2 for OER and 10 mA cm^?2 for HER, the Ru–MnFeP/NF electrode only requires overpotentials of 191 and 35 mV, respectively. Such high electrocatalytic activity exceeds most transition metal phosphides for the OER and the HER, and even reaches Pt‐like HER electrocatalytic levels. Accordingly, it significantly accelerates full water splitting at 10 mA cm^?2 with 1.470 V, which outperforms that of the integrated RuO₂ and Pt/C couple electrode (1.560 V). In addition, the extremely long operational stability (50 h) and the successful demonstration of a solar‐to‐hydrogen generation system through full water splitting provide more flexibility for large‐scale applications of Ru–MnFeP/NF catalysts.     

A naphthalene derivative as ‘turn‐on’ fluorescent chemosensor for the highly selective and sensitive detection of Al3+

A Schiff base compound derived from naphthalene has been synthesized and characterized as an Al³⁺‐selective fluorescent probe. The chemosensor ( L ) exhibits high selectively for Al³⁺ in aqueous solution, even in the presence of biologically relevant cations such as Na⁺, K⁺, Ca²⁺, Mg²⁺, Pb²⁺ and several transition metal ions. There was no observed interference from anions like Br^?, Cl^?, HSO₃^?, SO₃^2?, S₂O₃^2?, NO₂^?, CO₃^2? and AC^?. The lowest detection limit for the chemosensor L was found to be 1.89 × 10^?8 M with a linear response towards Al³⁺ over a concentration range of 5 × 10^?6 to 4 × 10^?5 M. Furthermore, the proposed chemosensor has been used for imaging of Al³⁺ in two different types of cells with satisfying results, which further demonstrates its value for practical application in biological systems.     

Drastic Layer‐Number‐Dependent Activity Enhancement in Photocatalytic H2 Evolution over nMoS2/CdS (n ≥ 1) Under Visible Light

Exploiting noble‐metal‐free cocatalysts is of huge interest for photocatalytic water splitting using solar energy. As an efficient cocatalyst in photocatalysis, MoS₂ is shown promise as a low‐cost alternative to Pt for hydrogen evolution. Here we report a systematical study on controlled synthesis of MoS₂ with layer number ranging from ≈1 to 112 and their activities for photocatalytic H₂ evolution over commercial CdS. A drastic increase in photocatalytic H₂ evolution is observed with decreasing MoS₂ layer number. Particularly for the single‐layer (SL) MoS₂, the SL‐MoS₂/CdS sample reaches a high H₂ generation rate of ≈2.01 × 10^?3m h^?1 in Na₂S–Na₂SO₃ solutions and ≈2.59 × 10^?3m h^?1 in lactic acid solutions, corresponding to an apparent quantum efficiency of 30.2% and 38.4% at 420 nm, respectively. In addition to the more exposed edges and unsaturated active S atoms, valence band–XPS and Mott–Schottky plots analysis indicate that the SL MoS₂ has the more negative conduction band energy level than the H⁺/H₂ potential, facilitating the hydrogen reduction.     

Perturbation of the tris(2,2′‐bipyridine) ruthenium(II)‐catalyzed Belousov–Zhabotinsky oscillating chemiluminescence reaction by l‐cysteine and its application

Perturbation of the tris(2,2′‐bipyridine)ruthenium(II) [Ru(bpy)₃²⁺]‐catalyzed Belousov–Zhabotinsky (BZ) oscillating chemiluminescence (CL) reaction induced by l ‐cysteine was observed in the closed system. It was found that the CL intensity was decreased in the presence of l ‐cysteine. Meanwhile, oscillation period and oscillating induction period were prolonged. The sufficient reproducible induction period was used as parameter for the analytical application of oscillating CL reaction. Under the optimum conditions, the changes in the oscillating CL induction period were linearly proportional to the concentration of l ‐cysteine in the range from 8.0 × 10^?7 to 5.0 × 10^?5 mol L^?1 (r = 0.997) with a detection limit of 4.3 × 10^?7 mol L^?1. The possible mechanism of l ‐cysteine perturbation on the oscillating CL reaction was also discussed. Copyright © 2009 John Wiley & Sons, Ltd.     

β‐Cell Function and Insulin Sensitivity in Adolescents From an OGTT

Given the increase in the incidence of insulin resistance, obesity, and type 2 diabetes in children and adolescents, it would be of paramount importance to assess quantitative indices of insulin secretion and action during a physiological perturbation, such as a meal or an oral glucose‐tolerance test (OGTT). A minimal model method is proposed to measure quantitative indices of insulin secretion and action in adolescents from an oral test. A 7 h, 21‐sample OGTT was performed in 11 adolescents. The C‐peptide minimal model was identified on C‐peptide and glucose data to quantify indices of β‐cell function: static φ_s and dynamic φ_d responsivity to glucose from which total responsivity φ was also measured. The glucose minimal model was identified on glucose and insulin data to estimate insulin sensitivity, S_I, which was compared to a reference measure, S_I^ref, provided by a tracer method. Disposition indices, which adjust insulin secretion for insulin action, were then calculated. Indices of β‐cell function were φ_s = 51.35 ± 8.89 × 10^?9min^?1, φ_d = 1,392 ± 258 × 10^?9, and φ = 82.09 ± 17.70 × 10^?9min^?1. Insulin sensitivity was S_I = 14.19 ± 2.73 × 10^?4, not significantly different from S_I^ref = 14.96 ± 3.04 × 10^?4 dl/kg·min per µU/ml, and well correlated: r = 0.98, P < 0.0001, thus indicating that S_I can be accurately measured from an oral test. Disposition indices were DI_s = 1,040 ± 201 × 10^?14 dl/kg/min² per pmol/l, DI_d = 33,178 ± 10,720 × 10^?14 dl/kg/min per pmol/l, DI = 1,844 ± 522 × 10^?14 dl/kg/min² per pmol/l. Virtually the same minimal model assessment was obtained with a reduced 3 h, 9‐sample protocol. OGTT interpreted with C‐peptide and glucose minimal model has the potential to provide novel insight regarding the regulation of glucose metabolism in adolescents, and to evaluate the effect of obesity and interventions such as diet and exercise.     

Electroless Plating of Highly Efficient Bifunctional Boride‐Based Electrodes toward Practical Overall Water Splitting

Exploring highly‐efficient and low‐cost electrodes for both hydrogen and oxygen evolution reaction (HER and OER) is of primary importance to economical water splitting. Herein, a series of novel and robust bifunctional boride‐based electrodes are successfully fabricated using a versatile Et₂NHBH₃‐involved electroless plating (EP) approach via deposition of nonprecious boride‐based catalysts on various substrates. Owing to the unique binder‐free porous nodule structure induced by the hydrogen release EP reaction, most of the nonprecious boride‐based electrodes are highly efficient for overall water splitting. As a distinctive example, the Co‐B/Ni electrode can afford 10 mA cm^?2 at overpotentials of only 70 mV for HER and 140 mV for OER, and can also survive at large current density of 1000 mA cm^?2 for over 20 h without performance degradation in 1.0 m KOH. Several boride‐based two‐electrode electrolyzers can achieve 10 mA cm^?2 at low voltages of around 1.4 V. Moreover, the facile EP approach is economically viable for flexible and large size electrode production.     

2‐Hydroxynaphthalene‐1‐carbaldehyde‐ and 2‐(Aminomethyl)pyridine‐Based Schiff Base CuII Complexes for DNA Binding and Cleavage

Three mononuclear Cu^II complexes, [CuCl(naph‐pa)] ( 1 ), [Cu(bipy)(naph‐pa)]Cl ( 2 ), and [Cu(naph‐pa)(phen)]Cl ( 3 ) ((naph‐pa)=Schiff base derived from the condensation of 2‐hydroxynaphthalene‐1‐carbaldehyde and 2‐picolylamine (=2‐(aminomethyl)pyridine), bipy=2,2′‐bypiridine, and phen=1,10‐phenanthroline) were synthesized and characterized. Complex 1 exhibits square‐planar geometry, and 2 and 3 exhibit square pyramidal geometry, where Schiff base and bipy/phen act as NNO and as NN donor ligands, respectively. CT (Calf thymus)‐DNA‐binding studies revealed that the complexes bind through intercalative mode and show good binding propensity (intrinsic binding constant K_b: 0.98×10⁵, 2.22×10⁵, and 2.67×10⁵ M ^?1 for 1 – 3 , resp.). The oxidative and hydrolytic DNA‐cleavage activity of these complexes has been studied by gel electrophoresis: all the complexes displayed chemical nuclease activity in the presence and absence of H₂O₂. From the kinetic experiments, hydrolytic DNA cleavage rate constants were determined as 2.48, 3.32, and 4.10 h^?1 for 1 – 3 , respectively. It amounts to (0.68–1.14)×10⁸‐fold rate enhancement compared to non‐catalyzed DNA cleavage, which is impressive. The complexes display binding and cleavage propensity to DNA in the order of 3 > 2 > 1 .     

High‐Performance Hydrogen Evolution by Ru Single Atoms and Nitrided‐Ru Nanoparticles Implanted on N‐Doped Graphitic Sheet

The most efficient electrocatalyst for the hydrogen evolution reaction (HER) is a Pt‐based catalyst, but its high cost and nonperfect efficiency hinder wide‐ranging industrial/technological applications. Here, an electrocatalyst of both ruthenium (Ru) single atoms (SAs) and N‐doped‐graphitic(G_N)‐shell‐covered nitrided‐Ru nanoparticles (NPs) (having a Ru‐N_x shell) embedded on melamine‐derived G_N matrix { 1 : [Ru(SA)+Ru(NP)@RuN_x@G_N]/G_N}, which exhibits superior HER activity in both acidic and basic media, is presented. In 0.5 m H₂SO₄/1 m KOH solutions, 1 shows diminutive “negative overpotentials” (?η = |η| = 10/7 mV at 10 mA cm^?2, lowest ever) and high exchange current densities (4.70/1.96 mA cm^?2). The remarkable HER performance is attributed to the near‐zero free energies for hydrogen adsorption/desorption on Ru(SAs) and the increased conductivity of melamine‐derived G_N sheets by the presence of nitrided‐Ru(NPs). The nitridation process forming nitrided‐Ru(NPs), which are imperfectly covered by a G_N shell, allows superb long‐term operation durability. The catalyst splits water into molecular oxygen and hydrogen at 1.50/1.40 V (in 0.1 m HClO₄/1 m KOH), demonstrating its potential as a ready‐to‐use, highly effective energy device for industrial applications.     

Direct Growth of Flower‐Like δ‐MnO2 on Three‐Dimensional Graphene for High‐Performance Rechargeable Li‐O2 Batteries

A challenge still remains to develop high‐performance and cost‐effective air electrode for Li‐O₂ batteries with high capacity, enhanced rate capability and long cycle life (100 times or above) despite recent advances in this field. In this work, a new design of binder‐free air electrode composed of three‐dimensional (3D) graphene (G) and flower‐like δ‐MnO₂ (3D‐G‐MnO₂) has been proposed. In this design, graphene and δ‐MnO₂ grow directly on the skeleton of Ni foam that inherits the interconnected 3D scaffold of Ni foam. Li‐O₂ batteries with 3D‐G‐MnO₂ electrode can yield a high discharge capacity of 3660 mAh g^?1 at 0.083 mA cm^?2. The battery can sustain 132 cycles at a capacity of 492 mAh g^?1 (1000 mAh g_carbon ^?1) with low overpotentials under a high current density of 0.333 mA cm^?2. A high average energy density of 1350 Wh Kg^?1 is maintained over 110 cycles at this high current density. The excellent catalytic activity of 3D‐G‐MnO₂ makes it an attractive air electrode for high‐performance Li‐O₂ batteries.     

Effect of CO2 on uninfected Sf‐9 cell growth and metabolism

A problem in the mass production of recombinant proteins and biopesticides using insect cell culture is CO₂ accumulation. This research investigated the effect of elevated CO₂ concentration on insect cell growth and metabolism. Spodoptera frugiperda Sf‐9 insect cells were grown at 20% air saturation, 27^°C, and a pH of 6.2. The cells were exposed to a constant CO₂ concentration by purging the medium with CO₂ and the headspace with air. The population doubling time (PDT) of Sf‐9 cells increased with increasing CO₂ concentration. Specifically, the PDT for 0‐37, 73, 147, 183, and 220 mm Hg CO₂ concentrations were 23.2 ± 6.7, 32.4 ± 7.2, 38.1 ± 13.3, 42.9 ± 5.4, and 69.3 ± 35.9 h (n = 3 or 4, 95% confidence level), respectively. The viability of cells in all experiments was above 90%, i.e., while increased CO₂ concentrations inhibited cell growth, it did not affect cell viability. The osmolality for all bioreactor experiments was observed to be 300–360 mOsm/kg, a range that is known to have a negligible effect on insect cell culture. Elevated CO₂ concentration did not significantly alter the cell specific glucose consumption rate (2.5–3.2 × 10^?17 mol/cell s), but slightly increased the specific lactate production rate from ?3.0 × 10^?19 to 10.2 × 10^?19 mol/cell s. Oxidative stress did not contribute to CO₂ inhibition in uninfected Sf‐9 cells as no significant increase in the levels of lipid hydroperoxide and protein carbonyl concentrations was discovered at elevated CO₂ concentration. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:465–469, 2016     

Ni–Fe–La(Sr)Fe(Mn)O3 as a New Active Cermet Cathode for Intermediate‐Temperature CO2 Electrolysis Using a LaGaO3‐Based Electrolyte

Various additives to Ni–Fe systems are studied as cermet cathodes for CO₂ electrolysis (973–1173 K) using a La_0.9Sr_0.1Ga_0.8Mg_0.2O₃ (LSGM) electrolyte, which is one of the most promising oxide‐ion conductors for intermediate‐temperature solid‐oxide electrolysis cells in terms of ionic‐transport number and conductivity. It is found that Ni–Fe–La_0.6Sr_0.4Fe_0.8Mn_0.2O₃ (Ni–Fe–LSFM) exhibits a remarkable performance with a current density of 2.32 A cm^?2 at 1.6 V and 1073 K. The cathodic overpotential is significantly decreased by mixing the LSFM powder with Ni–Fe, which is related to the increase in the number of reaction sites for CO₂ reduction. For Ni–Fe–LSFM, much smaller particles (<200 nm) are sustained under CO₂ electrolysis conditions at high temperatures than for Ni–Fe. X‐ray diffraction analysis suggests that the main phases of Ni–Fe–LSFM are Ni and LaFeO₃; thus, the oxide phase of LaFeO₃ is also maintained during CO₂ electrolysis. Analysis of the gaseous products indicates that only CO is formed, and the rate of CO formation agrees well with that of a four‐electron reduction process, suggesting that the reduction of CO₂ to CO proceeds selectively. It is also confirmed that almost no coke is deposited on the Ni–Fe–LSFM cathode after CO₂ electrolysis.     

Determination of ketotifen fumarate by capillary electrophoresis with tris(2,2′‐bipyridyl) ruthenium(II) electrochemiluminescence detection

On the basis of an europium (III)‐doped Prussian blue analog film modifying platinum electrode as the working electrode, a Ru(bpy)₃²⁺‐based electrochemiluminescence (ECL) assay coupled with capillary electrophoresis has been first established for the determination of ketotifen fumarate (KTF). Analytes were injected onto a separation capillary of 50 cm length (50 μm i.d., 360 μm o.d.) by electrokinetic injection for 10 s at 10 kV. Parameters related to the separation and detection were discussed and optimized. It was proved that 15 mm phosphate buffer at pH 8.0 could achieve the most favorable resolution, and the highest sensitivity of detection was obtained using the detection potential at 1.25 V and 5 mm Ru(bpy)₃²⁺ in 100 mm phosphate buffer at pH 8.0 in the detection reservoir. Under the optimized conditions, the ECL intensity was in proportion to KTF concentration over the range from 3.0 × 10^?8 to 5.0 × 10^?6 g mL^?1 with a detection limit of 2.1 × 10^?8 g mL^?1 (3σ). The relative standard deviations of the ECL intensity and the migration time were 0.95 and 0.26%, respectively. The developed method was successfully applied to determine KTF contents in pharmaceuticals and human urine with recoveries between 99.5 and 107.0%. Copyright © 2010 John Wiley & Sons, Ltd.     

Mechanistic Study Revealing the Role of the Br3−/Br2 Redox Couple in CO2‐Assisted Li–O2 Batteries

Replacing oxygen (O₂) with air is a critical step in the development of lithium (Li)–air batteries. A trace amount of carbon dioxide (CO₂) in the air is, however, influentially involved in the O₂ chemistry, which indicates that a fundamental understanding of the effect of CO₂ is required for the design of practical cells. When up to 30% CO₂ is added to Li–O₂ cells, CO₂ acts as an O₂^? scavenger. Their chemical reactions form soluble products, CO₄^2? and C₂O₆^2?, in the tetraglyme electrolyte solution, and enhance full capacity and cell cyclability. A critical challenge is, however, the sluggish decomposition of the coproduct Li₂CO₃ during recharge. To lower the charging overpotential, a Br₃^?/Br₂ redox couple is incorporated and its redox behavior is investigated using spectroscopic methods. The redox shuttle of Br₃^?/Br₂ decomposes amorphous Li₂CO₃ more efficiently than its crystalline counterpart. It is revealed that Br₂ combines with Br₃^? to form a Br₂···Br₃^? complex, which acts as a mobile catalyst in the electrolyte solution without swift precipitation of the nonpolar Br₂. This comprehensive study, revealing the molecular structure and redox process of mobile catalysts, provides an insight into improving the design of redox couples toward superior cycling performance.     

Synthesis of Large Surface‐Area g‐C3N4 Comodified with MnOx and Au‐TiO2 as Efficient Visible‐Light Photocatalysts for Fuel Production

Herein, this study successfully fabricates porous g‐C₃N₄‐based nanocomposites by decorating sheet‐like nanostructured MnO_x and subsequently coupling Au‐modified nanocrystalline TiO₂. It is clearly demonstrated that the as‐prepared amount‐optimized nanocomposite exhibits exceptional visible‐light photocatalytic activities for CO₂ conversion to CH₄ and for H₂ evolution, respectively by ≈28‐time (140 µmol g^?1 h^?1) and ≈31‐time (313 µmol g^?1 h^?1) enhancement compared to the widely accepted outstanding g‐C₃N₄ prepared with urea as the raw material, along with the calculated quantum efficiencies of ≈4.92% and 2.78% at 420 nm wavelength. It is confirmed mainly based on the steady‐state surface photovoltage spectra, transient‐state surface photovoltage responses, fluorescence spectra related to the produced ?OH amount, and electrochemical reduction curves that the exceptional photoactivities are comprehensively attributed to the large surface area (85.5 m² g^?1) due to the porous structure, to the greatly enhanced charge separation and to the introduced catalytic functions to the carrier‐related redox reactions by decorating MnO_x and coupling Au‐TiO₂, respectively, to modulate holes and electrons. Moreover, it is suggested mainly based on the photocatalytic experiments of CO₂ reduction with isotope ¹³CO₂ and D₂O that the produced ?CO₂ and ?H as active radicals would be dominant to initiate the conversion of CO₂ to CH₄.