scholarly journals Function-oriented design of robust metal cocatalyst for photocatalytic hydrogen evolution on metal/titania composites

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Dong Wang ◽  
Xue-Qing Gong
Keyword(s):  
Electron Transfer ◽  
Hydrogen Evolution ◽  
Density Functional ◽  
Metal Layer ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Metal Type ◽  
Surface Catalysis ◽  
The Individual ◽  
The Right

AbstractWhile the precise design of catalysts is one of ultimate goals in catalysis, practical strategies often fall short, especially for complicated photocatalytic processes. Here, taking the hydrogen evolution reaction (HER) as an example, we introduce a theoretical approach for designing robust metal cocatalysts supported on TiO2 using density functional theory calculations adopting on-site Coulomb correction and/or hybrid functionals. The approach starts with clarifying the individual function of each metal layer of metal/TiO2 composites in photocatalytic HER, covering both the electron transfer and surface catalysis aspects, followed by conducting a function-oriented optimization via exploring competent candidates. With this approach, we successfully determine and verify bimetallic Pt/Rh/TiO2 and Pt/Cu/TiO2 catalysts to be robust substitutes for conventional Pt/TiO2. The right metal type as well as the proper stacking sequence are demonstrated to be key to boosting performance. Moreover, we tentatively identify the tunneling barrier height as an effective descriptor for the important electron transfer process in photocatalysis on metal/oxide catalysts. We believe that this study pushes forward the frontier of photocatalyst design towards higher water splitting efficiency.

scholarly journals Function-oriented Design of Robust Metal Cocatalyst for Photocatalytic Hydrogen Evolution on Metal/Titania Composites

2020 ◽  
Author(s):  
Dong Wang ◽  
Xue-Qing Gong
Keyword(s):  
Electron Transfer ◽  
Hydrogen Evolution ◽  
Density Functional ◽  
Rational Design ◽  
Metal Layer ◽  
Density Functional Theory Calculations ◽  
Effective Electron ◽  
Photocatalytic Reactions ◽  
The Individual ◽  
The Right

Abstract To realize the rational design of improved catalysts is one of ultimate goals in catalysis, though practical strategies are generally in shortage, especially for the complicated photocatalytic processes. Here, we take the hydrogen evolution reaction (HER) as an example, and introduce a theoretical approach for designing robust metal cocatalysts supported on TiO2, using density functional theory calculations adopting on-site Coulomb correction and/or hybrid functionals. The approach starts with clarifying the individual function of each metal layer of metal/TiO2 composites in photocatalytic HER, covering both the electron transfer and surface catalysis aspects, followed by conducting a function-oriented optimization via exploring competent candidates. With this approach, we successfully determined and verified bimetallic Pt/Rh/TiO2 and Pt/Cu/TiO2 catalysts to be robust substitutes for conventional Pt/TiO2. The right metal type as well as the proper stacking sequence are demonstrated to be the key to boosting the performance. Moreover, we pioneeringly identified the tunneling barrier height as an effective electron transfer descriptor for photocatalytic reactions on metal/oxide catalysts. We believe that this study pushes forward the frontier of photocatalyst design towards higher water splitting efficiency.

scholarly journals Spectroscopic evidence for direct flavin-flavin contact in a bifurcating electron transfer flavoprotein

2020 ◽  
Vol 295 (36) ◽  
pp. 12618-12634
Author(s):  
H. Diessel Duan ◽  
Nishya Mohamed-Raseek ◽  
Anne-Frances Miller
Keyword(s):  
Electron Transfer ◽  
Density Functional ◽  
Protein Denaturation ◽  
Rhodopseudomonas Palustris ◽  
Density Functional Theory Calculations ◽  
Site Directed Mutagenesis ◽  
Functional Theory ◽  
Electron Transfer Flavoprotein ◽  
Midpoint Potential ◽  
Ct Complex

A remarkable charge transfer (CT) band is described in the bifurcating electron transfer flavoprotein (Bf-ETF) from Rhodopseudomonas palustris (RpaETF). RpaETF contains two FADs that play contrasting roles in electron bifurcation. The Bf-FAD accepts electrons pairwise from NADH, directs one to a lower-reduction midpoint potential (E°) carrier, and the other to the higher-E° electron transfer FAD (ET-FAD). Previous work noted that a CT band at 726 nm formed when ET-FAD was reduced and Bf-FAD was oxidized, suggesting that both flavins participate. However, existing crystal structures place them too far apart to interact directly. We present biochemical experiments addressing this conundrum and elucidating the nature of this CT species. We observed that RpaETF missing either FAD lacked the 726 nm band. Site-directed mutagenesis near either FAD produced altered yields of the CT species, supporting involvement of both flavins. The residue substitutions did not alter the absorption maximum of the signal, ruling out contributions from residue orbitals. Instead, we propose that the residue identities modulate the population of a protein conformation that brings the ET-flavin and Bf-flavin into direct contact, explaining the 726 nm band based on a CT complex of reduced ET-FAD and oxidized Bf-FAD. This is corroborated by persistence of the 726 nm species during gentle protein denaturation and simple density functional theory calculations of flavin dimers. Although such a CT complex has been demonstrated for free flavins, this is the first observation of such, to our knowledge, in an enzyme. Thus, Bf-ETFs may optimize electron transfer efficiency by enabling direct flavin-flavin contact.

scholarly journals Exposing unsaturated Cu1-O2 sites in nanoscale Cu-MOF for efficient electrocatalytic hydrogen evolution

2021 ◽  
Vol 7 (18) ◽  
pp. eabg2580
Author(s):  
Weiren Cheng ◽  
Huabin Zhang ◽  
Deyan Luan ◽  
Xiong Wen (David) Lou
Keyword(s):  
Hydrogen Evolution ◽  
Density Functional ◽  
Metal Organic Framework ◽  
Density Functional Theory Calculations ◽  
Active Centers ◽  
Functional Theory ◽  
Hollow Nanostructure ◽  
Metal Organic ◽  
X Ray Absorption ◽  
A Current

Conductive metal-organic framework (MOF) materials have been recently considered as effective electrocatalysts. However, they usually suffer from two major drawbacks, poor electrochemical stability and low electrocatalytic activity in bulk form. Here, we have developed a rational strategy to fabricate a promising electrocatalyst composed of a nanoscale conductive copper-based MOF (Cu-MOF) layer fully supported over synergetic iron hydr(oxy)oxide [Fe(OH)x] nanoboxes. Owing to the highly exposed active centers, enhanced charge transfer, and robust hollow nanostructure, the obtained Fe(OH)x@Cu-MOF nanoboxes exhibit superior activity and stability for the electrocatalytic hydrogen evolution reaction (HER). Specifically, it needs an overpotential of 112 mV to reach a current density of 10 mA cm−2 with a small Tafel slope of 76 mV dec−1. X-ray absorption fine structure spectroscopy combined with density functional theory calculations unravels that the highly exposed coordinatively unsaturated Cu1-O2 centers could effectively accelerate the formation of key *H intermediates toward fast HER kinetics.

scholarly journals First-Principles Mechanistic Insights into the Hydrogen Evolution Reaction on Ni2P Electrocatalyst in Alkaline Medium

Catalysts ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 307
Author(s):  
Russell W. Cross ◽  
Nelson Y. Dzade
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Density Functional ◽  
Hydrogen Adsorption ◽  
Density Functional Theory Calculations ◽  
Transition Metal Doping ◽  
Experimental Conditions ◽  
Functional Theory ◽  
Alkaline Conditions ◽  
Modification Of The Surface

Nickel phosphide (Ni2P) is a promising material for the electrocatalytic generation of hydrogen from water. Here, we present a chemical picture of the fundamental mechanism of Volmer–Tafel steps in hydrogen evolution reaction (HER) activity under alkaline conditions at the (0001) and (10 1 ¯ 0) surfaces of Ni2P using dispersion-corrected density functional theory calculations. Two terminations of each surface (Ni3P2- and Ni3P-terminated (0001); and Ni2P- and NiP-terminated (10 1 ¯ 0)), which have been shown to coexist in Ni2P samples depending on the experimental conditions, were studied. Water adsorption on the different terminations of the Ni2P (0001) and (10 1 ¯ 0) surfaces is shown to be exothermic (binding energy in the range of 0.33−0.68 eV) and characterized by negligible charge transfer to/from the catalyst surface (0.01−0.04 e−). High activation energy barriers (0.86−1.53 eV) were predicted for the dissociation of water on each termination of the Ni2P (0001) and (10 1 ¯ 0) surfaces, indicating sluggish kinetics for the initial Volmer step in the hydrogen evolution reaction over a Ni2P catalyst. Based on the predicted Gibbs free energy of hydrogen adsorption (ΔGH*) at different surface sites, we found that the presence of Ni3-hollow sites on the (0001) surface and bridge Ni-Ni sites on the (10 1 ¯ 0) surface bind the H atom too strongly. To achieve facile kinetics for both the Volmer and Heyrovsky–Tafel steps, modification of the surface structure and tuning of the electronic properties through transition metal doping is recommended as an important strategy.

Two dimensional MoS2 meets porphyrins via intercalation to enhance the electrocatalytic activity toward hydrogen evolution

Nanoscale ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 3780-3785 ◽  
Author(s):  
Ik Seon Kwon ◽  
In Hye Kwak ◽  
Hafiz Ghulam Abbas ◽  
Hee Won Seo ◽  
Jaemin Seo ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Electrocatalytic Activity ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Two Dimensional ◽  
Functional Theory ◽  
Spin Polarized

Mn-Porphyrin-MoS2 exhibits excellent electrocatalytic activity toward the hydrogen evolution reaction, which is supported by spin-polarized density functional theory calculations.

Intercalation of cobaltocene into WS2 nanosheets for enhanced catalytic hydrogen evolution reaction

2019 ◽  
Vol 7 (14) ◽  
pp. 8101-8106 ◽  
Author(s):  
In Hye Kwak ◽  
Hafiz Ghulam Abbas ◽  
Ik Seon Kwon ◽  
Yun Chang Park ◽  
Jaemin Seo ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Spin Polarized ◽  
Catalytic Hydrogen ◽  
Catalytic Hydrogen Evolution ◽  
Ws2 Nanosheets

Cobaltocene-intercalated WS2 nanosheets exhibit excellent catalytic activity toward the hydrogen evolution reaction, which is supported by spin-polarized density functional theory calculations.

Mechanistic Study of ROS-photogeneration by Pterin

Pteridines ◽  
2011 ◽  
Vol 22 (1) ◽  
pp. 73-76 ◽  
Author(s):  
Hong-Fang Ji ◽  
Liang Shen
Keyword(s):  
Electron Transfer ◽  
Density Functional ◽  
Transfer Reaction ◽  
Direct Electron Transfer ◽  
Density Functional Theory Calculations ◽  
Electron Transfer Reaction ◽  
Mechanistic Study ◽  
Functional Theory ◽  
Direct Energy ◽  
Electronic Parameters

Abstract Pterins are widespread in biological systems and possess photosensitizing activities. In the present study, the photosensitization mechanism of acid form of pterin (PTA) and basic form of pterin (PTB) is investigated by means of density functional theory calculations. The reactive oxygen species-photogenerating pathways of the lowest triplet excited (T1) state PTA and PTB are proposed as follows. Through direct energy transfer, both T1 state PTA and PTB can photogenerate 1O2. Two possible O2 .−-generating pathways are proposed according to the electronic parameters of PTA and PTB: i) direct electron transfer from T1 state PTA and PTB to 3O2 and the electron transfer reaction is more favorable energetically for PTB in comparison with PTA; and ii) electron transfer from anion radical of PTA and PTB to 3O2.

Metal carbonyl complexes of potentially ambidentate 2,1,3-benzothiadiazole and 2,1,3-benzoselenadiazole acceptors

2017 ◽  
Vol 72 (11) ◽  
pp. 839-846
Author(s):  
Sebastian Plebst ◽  
Martina Bubrin ◽  
David Schweinfurth ◽  
Stanislav Záliš ◽  
Wolfgang Kaim
Keyword(s):  
Crystal Structure ◽  
Density Functional Theory ◽  
Electron Transfer ◽  
Density Functional ◽  
Metal Carbonyl ◽  
Density Functional Theory Calculations ◽  
Carbonyl Complexes ◽  
Functional Theory ◽  
Metal Carbonyl Complexes ◽  
Reduced Forms

AbstractThe compounds [W(CO)5(btd)], [W(CO)5(bsd] and [Re(CO)3(bpy)(bsd)](BF4), btd=2,1,3-benzothiadiazole and bsd=2,1,3-benzoselenadiazole were isolated and characterized experimentally (crystal structure, spectroscopy, spectroelectrochemistry) and by density functional theory calculations. The results confirm single N-coordination in all cases, binding to Se was calculated to be less favorable. Studies of one-electron reduced forms indicate that the N-coordination is maintained during electron transfer.

scholarly journals Electron Transfer to CO2 during Adsorption at the Metal | Solution Interface

2019 ◽  
Author(s):  
Michal Bajdich ◽  
Meredith Fields ◽  
Leanne D. Chen ◽  
Robert B. Sandberg ◽  
Karen Chan ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Density Functional ◽  
Degrees Of Freedom ◽  
Adsorption Process ◽  
Density Functional Theory Calculations ◽  
High Rate ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Generalized Gradient Approximation ◽  
Solution Interface

<i>We estimate the rate of electron transfer to CO<sub>2</sub> at the Au(211)|water interface during adsorption in an electrochemical environment under negative potentials. Based on density functional theory calculations at the generalized gradient approximation, hybrid, and GW levels of theory, we find electron transfer to adsorbed *CO<sub>2</sub> to be very facile. This high rate of transfer is estimated by the energy distribution of the adsorbate-induced density of states as well as from the interaction between diabatic states representing neutral and negatively charged CO<sub>2</sub>. Up to 0.54 electrons is transferred to CO<sub>2</sub>, and this charge adiabatically increases with the bending angle to a lower limit of 140°. We conclude that this rate of electron transfer is extremely fast compared to the timescale of the nuclear degrees of freedom, that is, the adsorption process</i><br>

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