Abstract
Single-atom catalysts with maximum metal utilization efficiency show great potential for sustainable catalytic applications and fundamental mechanistic studies. We here provide a convenient ...molecular tailoring strategy based on graphitic carbon nitride as support for the rational design of single-site and dual-site single-atom catalysts. Catalysts with single Fe sites exhibit impressive oxygen reduction reaction activity with a half-wave potential of 0.89 V vs. RHE. We find that the single Ni sites are favorable to promote the key structural reconstruction into bridging Ni-O-Fe bonds in dual-site NiFe SAC. Meanwhile, the newly formed Ni-O-Fe bonds create spin channels for electron transfer, resulting in a significant improvement of the oxygen evolution reaction activity with an overpotential of 270 mV at 10 mA cm
−2
. We further reveal that the water oxidation reaction follows a dual-site pathway through the deprotonation of *OH at both Ni and Fe sites, leading to the formation of bridging O
2
atop the Ni-O-Fe sites.
Photocatalytic hydrogen evolution is a promising technique for the direct conversion of solar energy into chemical fuels. Colloidal quantum dots with tunable band gap and versatile surface properties ...remain among the most prominent targets in photocatalysis despite their frequent toxicity, which is detrimental for environmentally friendly technological implementations. In the present work, all-inorganic sulfide-capped InP and InP/ZnS quantum dots are introduced as competitive and far less toxic alternatives for photocatalytic hydrogen evolution in aqueous solution, reaching turnover numbers up to 128,000 based on quantum dots with a maximum internal quantum yield of 31%. In addition to the favorable band gap of InP quantum dots, in-depth studies show that the high efficiency also arises from successful ligand engineering with sulfide ions. Due to their small size and outstanding hole capture properties, sulfide ions effectively extract holes from quantum dots for exciton separation and decrease the physical and electrical barriers for charge transfer.
In this work, the influence of the terminating or exposed crystal planes of anatase TiO2 support on the catalytic activity of Pt/TiO2 catalysts is reported. Strong effects were observed when using CO ...oxidation as a probe reaction. The CO oxidation activity over these catalysts ranks in the following order: Pt/TiO2-{101} > Pt/TiO2-{100} > Pt/TiO2-{001}. The combination of in situ X-ray absorption spectroscopy, X-ray emission spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy, and density functional theory calculations unravelled a strong interaction between platinum particles and different dominating facets of anatase. The catalytic activity of the Pt/TiO2 catalysts can be correlated with the spectroscopic/structural results. Compared to {001} facets, the {100} and {101} facets of TiO2 can stabilize active highly dispersed Pt species and avoid sintering Pt particles. This finding provides some important insights into understanding the metal–support interfacial interactions of Pt/TiO2 catalysts for tuning their catalytic performance.
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IJS, KILJ, NUK, PNG, UL, UM
Research on Fe3+ reduction coupled to anaerobic ammonium oxidation (Feammox) and its associated processes in the moderately low-dissolved oxygen (DO) urban natural environment is lacking. To clarify ...seasonal and spatial variations in Feammox, iron-reducing, and anaerobic ammonium oxidation (anammox) in urban green spaces, we examined the physicochemical indices and functional genes acd, acm, Geo, and hszA in topsoils and wetland soils across four seasons. Further, we performed 16S rRNA high-throughput sequencing. The Feammox-related gene acm was detected in all topsoil samples. Season and habitat affected soil physicochemical indices influencing gene distributions. Moisture content (45.3%) and Fe3+ (13.3%) mediated genetic changes. Competition between Feammox and iron-reducing bacteria (IRB) lowered the distributions of acd and acm in summer and increased these in winter. The acd and acm distributions were higher in wetland soil than in forestland soil. The dominant phyla, Nitrospirota, Actinobacteriota, and Desulfobacterota, correlated positively. Network analysis revealed that the relative abundances of acd, Geo, and hszA correlated positively with Flavobacterium and Thermomonas, Subgroup_2, and Candidatus_Solibacter, respectively. Feammox, iron-reducing, and anammox microorganisms correlated positively but competition existed between certain taxa. Candidatus, Sphingomonas, and Geobacter are linked to Feammox, iron reduction, and anammox. Here, we demonstrated the theoretical feasibility of developing Feammox-based nitrogen removal technology under moderately low-DO conditions, providing a reference for elucidating the ecological contribution of Feammox in an urban green heart.
Multiple morphologies of colloidal perovskite nanocrystals (NCs) diversify their optical and electronic properties. Among them, the linear absorption cross-section (
σ
) is a primary parameter to ...determine their intrinsic photophysical features, and consequently, application potential. Herein, three morphologies of all-inorganic hybrid colloidal perovskite CsPbBr
3
NCs, nanocubes (NBs), nanoplatelets (NLs), and nanowires (NWs), were targeted, and their linear
σ
values were obtained through femtosecond transient absorption (TA) spectroscopy analysis. At high excitation energy well above the bandgap, the
σ
per particle of all CsPbBr
3
NCs linearly increased with the particle volume (
V
NC
) regardless of the morphology with the value of
σ
400
= 9.45 × 10
4
cm
−1
×
V
NC
(cm
2
). Density functional theory (DFT) calculation confirmed the negligible influence of shapes on the optical selection rules. The Einstein spontaneous emission coefficients calculated from the
σ
values define the intrinsic radiative recombination rate. However, reduced size dependence is observed when the excitation energy is close to the bandgap (i.e., at 460 nm) with the value of
σ
460
= 2.82 × 10
8
cm
0.65
× (
V
NC
)
0.45
(cm
2
). This should be ascribed to the discrete energy levels as well as lower density of states close to the band edge for perovskite NCs. These results provide in-depth insight into the optical characteristics for perovskite NCs.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In this study, DFT-D calculations were performed to explore the role of Cu and Mo loading in the CO2 conversion mechanism on a two-dimensional g-C3N4(001) surface. The introduced transition metals, ...Cu and Mo, significantly changed the electron distribution and band structures of g-C3N4. Moreover, two possible mechanisms for the reduction of CO2 to CO have been discussed in detail. We found that the energy barriers of the two mechanisms were largely reduced by Cu and Mo loading, and the dominant reaction path changed on different transition metal-loaded surfaces. Cu/g-C3N4(001) prefers to directly dissociate CO2 into CO, whereas cis-COOH is the preferred product of CO2 reduction on Mo/g-C3N4(001). Considering the activation barrier and reaction route selectivity, Mo-doped g-C3N4(001) was identified as a promising candidate for CO2 conversion. It is concluded that suitable transition metal doping can efficiently reduce the energy barrier and control route selectivity along the reaction paths over the g-C3N4 surface. These findings could provide a helpful understanding of the CO2 reduction mechanisms and aid in the molecular design of novel g-C3N4 catalysts for CO2 conversion.
As hydrogen sulfide (H2S) is a toxic chemical emitted in large quantities from both natural sources and industrial processes, resource utilization of H2S has become a hotspot research in recent ...years. We report herein, synthesis and characterization of a highly active In2S3/CuS nanosheet composite photocatalyst via a facile one-pot solvothermal route. The as-obtained In2S3/CuS composite show a special hierarchical structure and remarkable visible light absorption ability with an absorption edge of 785 nm. Its remarkable light absorption ability enables it to fully absorb the visible light. The as-obtained In2S3/CuS composite exhibits a superior visible-light photocatalytic activity and long-term durability in H2S splitting. As a result, a maximum H2 production rate of 14950 μmol g−1 h−1 over In2S3/CuS composite has been achieved even without any noble metal co-catalysts, which is 404 and 87 fold higher than that of over bare β-In2S3 and Cu9S5, respectively. The corresponding apparent quantum yield (AQY) of In2S3/CuS at 420 nm is 9.3%. The excellent photocatalytic activity depends on the chemical structure, phase, optical nature and folded nanosheet like geometry of In2S3/CuS composite, which facilitated electron transfer between interfaces of β-In2S3 and CuS, and improved the separation of photogenerated electron-hole pairs. Therefore, In2S3/CuS composite could serve as an efficient and practical visible-light response photocatalyst for H2 production from toxic and corrosive H2S.
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•In2S3/CuS composite was successfully prepared by one-pot solvothermal method with superior visible-light absorption ability.•In2S3/CuS composite exhibits impressive high activity and superior stability for photocatalytic H2 production from H2S.•H2 production rate of 14950 μmol g−1 h−1 can be achieved over In2S3/CuS composite under the visible-light irradiation.•The reaction medium containing SO32- and S2- can suppress the formation of yellow S22- and solid S, favoring the long-term H2 production.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The options of transition metals as co-catalysts for photocatalytic H2S splitting are restricted to some noble metals and related compounds which have noticeable achievements despite their high ...prices. Substituting with cheap transition metals and downsizing the size to single atom level are economic ways to lower the cost. Herein, the s-triazine graphite-like carbon nitride sheet g-C3N4 (001) is chosen as the model to study the performances of 3d and 4d transition metal single atoms (TMSA = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd) in H2S splitting based on density functional theory (DFT) calculations. It is found that low-cost transition metals with industrial relevance (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Tc, Cd) are completely comparable with noble metals (Ru, Rh, Pd, Ag). Among them, V and Nb are the most promising co-catalysts with good thermodynamic stabilities, favorable responses to visible light, high photoinduced electron-hole separation efficiencies, sufficient potentials for H2S splitting, and low energy barriers for H2S dissociation into H2 and S. The noticeable improved activities of V/g-C3N4 and Nb/g-C3N4 are attributed to the formation of strong interfacial chemical bonds which could promote electrons transferring to H2S derivates. In addition, the introduction of photoinduced electrons could further improve the activities of V/g-C3N4 and Nb/g-C3N4 with more electrons transferring to H2S derivates. It is expected that this work could provide a helpful guidance to choose appropriate TMSA co-catalysts as references for H2S splitting.
Vanadium (V) and Niobium (Nb) as the most promising co-catalysts for hydrogen sulfide (H2S) splitting screened out from 3d and 4d transition metal single atoms Display omitted
•Low-cost transition metals as co-catalysts are comparable with noble metals.•V and Nb are the most promising co-catalysts for H2S splitting.•The improved activity is attributed to enhanced interfacial charge transfer.•Photoinduced electrons could further promote interfacial charge transfer.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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H2S is a notorious gas widely generated in the petrochemical industry. How to handle H2S effectively and convert it into highly-valued products is vital. Photocatalysis is promising ...in this field, as it could directly utilize solar light and convert H2S into H2 and S. In this review, the properties of hydrogen sulfide (H2S) is overviewed first, and conventional techniques (Claus process, thermolysis, non-thermal plasma, electrochemistry and other methods) for H2S conversion are simply introduced. Basic knowledge of photocatalysis and general strategies for enhancing the activities of photocatalysts are presented as well. Then typical work for photocatalytic conversion of H2S in gas phase and liquid phase are introduced case by case, with the generated H2 as the main product in these systems. Furthermore, methods for extraction of elemental sulfur from H2S by photocatalysis-related methods were discussed, with specific attention on photoelectrochemical cells and photovoltaic-electrochemical cells. In the end, current status of the research on photocatalytic conversion of H2S is summarized, and challenges in this field is put forward. In addition, some other possible strategies for photocatalytic conversion of H2S into highly-valued chemicals instead of hydrogen and elemental sulfur will be discussed, which is aimed to inspire researchers interested in this field.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The interfacial coupling promoting H2S splitting on the staggered type II g-C3N4/r-TiO2 heterojunction.
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•The g-C3N4/r-TiO2 is determined to a staggered type II heterojunction.•The ...potentials of g-C3N4/r-TiO2 are adequate for H2S splitting.•The interfacial coupling effect of g-C3N4/r-TiO2 could promote H2S splitting.•The r-TiO2 (1 1 0) is the active surface of g-C3N4/r-TiO2 for H2S dissociation.•The g-C3N4 (0 0 1) is the active surface of g-C3N4/r-TiO2 for H2 and S production.
Hydrogen (H2) production and sulfur (S) recovery by hydrogen sulfide (H2S) photo-splitting is an ideal strategy to remove the hazardous gas and simultaneously turn the waste into clean energy and industrial resources. For this purpose, the highly photocatalytic activity of heterojunctions has attracted worldwide attention in H2S splitting. However, the intricate mechanism of interfacial coupling effect on the whole process of H2S photo-splitting, including light absorption, photoinduced carrier separation and surface reactions, restricts the design and construction of highly efficient heterojunctions. This work devotes to illuminating the interfacial coupling effect from these three aspects by constructing g-C3N4/r-TiO2 heterojunction based on the density functional theory (DFT). The reduced band gap of g-C3N4/r-TiO2 is beneficial to enhance the visible-light absorption. Photoinduced carriers could be efficiently separated in the staggered type II g-C3N4/r-TiO2 heterojunction which possesses sufficient redox potentials for H2S splitting into H2 and S. Particularly, the r-TiO2 (1 1 0) and g-C3N4 (0 0 1) are the active surfaces of g-C3N4/r-TiO2 for H2S dissociation and H2 production, respectively. More importantly, the interfacial coupling effect of g-C3N4/r-TiO2 could facilitate H2S dissociation by reducing the reaction energy barriers and promote the desorption of S to avoid the deactivation of g-C3N4/r-TiO2. Given the different functions of r-TiO2 (1 1 0) and g-C3N4 (0 0 1), the exposure of r-TiO2 (1 1 0) is crucial to the activity of g-C3N4/r-TiO2 during the design and fabrication of g-C3N4/r-TiO2 for H2S splitting. This work could provide novel insights into the interfacial coupling effect on the surface reactions and offer helpful guidance for constructing efficient heterojunctions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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