Electron-donating Effect Research Articles

Superior nitrate and chromium reduction synergistically driven by multiple electron donors: Performance and the related biochemical mechanism

Nitrate and Cr(VI) are the typical and prevalent co-contaminants in the groundwater, how to synchronously and effectively diminish them has received growing attention. The most problem that currently limits the nitrate and Cr(VI) reduction technology for groundwater remediation is with emphasis on exploring the optimal electron donors. This study investigated the feasibility of utilizing the synergistical effect of inorganic electron donors (pyrite, sulfur) and inherently limited organics to promote synchronous nitrate and Cr(VI) removal, which meets the requirement of naturally low-carbon and eco-friendly technologies. The NO3−-N and Cr(VI) removal efficiencies in the pyrite and sulfur involved mixotrophic biofilter (PS–BF: approximately 90.8 ± 0.6% and 99.1 ± 2.1%) were substantially higher than that in a volcanic rock supported biofilter (V–BF: about 49.6% ± 2.8% and 50.0% ± 9.3%), which was consistent with the spatial variations of their concentrations. Abiotic and biotic batch tests directly confirmed the decisive role of pyrite and sulfur for NO3−-N and Cr(VI) removal via chemical and microbial pathways. A server decline in sulfate production correlated with decreasing COD consumption revealed that there was sulfur disproportionation induced by limited organics. Metagenomic analysis suggested that chemoautotrophic microbes like Sulfuritalea and Thiobacillus were key players responsible for sulfur oxidation, nitrate and Cr(VI) reduction. The metabolic pathway analysis suggested that genes encoding functional enzymes related to complete denitrification, S oxidation, and dissimilatory sulfate reduction were upregulated, however, genes encoding Cr(VI) reduction enzymes (e.g. chrA, chrR, nemA, and azoR) were downregulated in PS-BF, which further explained the synergistical effect of multiple electron donors. These findings provide insights into their potential cooperative interaction of multiple electron donors on greatly promoting nitrate and Cr(VI) removal and have implications for the remediation technology of nitrate and Cr(VI) co-contaminated groundwater.

Radical-mediated oxidative desulfurization of dibenzothiophene in a chromophore-enhanced photocatalytic system

This study presents a refined photocatalytic oxidative desulfurization (PODS) approach, leveraging a chromophore-enhanced system specifically designed for the selective degradation of dibenzothiophene (DBT). Employing a ruthenium-based complex (RuL) as a model sensitizer that can be activated by visible light, the system catalytically decomposes peroxydisulfate (S2O82−) into highly reactive radical species, key agents in facilitating efficient sulfur oxidation. In this system, the oxidative degradation of DBT proceeds through a well-defined pathway, sequentially transforming DBT into its sulfoxide (DBT-O) and subsequently into its sulfone (DBT-O2) derivatives, achieving nearly complete conversion to DBT-O2. The electron transfer dynamics within this photocatalytic system are examined through a concentration-dependent decrease in photoluminescence. Moreover, the effects of various electron donors and acceptors on the system’s catalytic activity, as well as the influence of structural modifications of the ruthenium sensitizer are investigated. Comparative evaluations with an alternative 9,10-dicyanoanthracene (DCA)-sensitized system underscore the superior efficiency and selectivity of the sulfate and/or hydroxyl radicals generated in the RuL/S2O82− system. Unlike the superoxide radicals produced in the DCA-sensitized system, the radicals generated in the RuL/S2O82− system exhibit significantly enhanced kinetics for DBT oxidation. The RuL/S2O82− photocatalytic system operates effectively under milder conditions without requiring hydrogen, positioning it as a promising alternative for sulfur removal and potentially contributing to more environmentally sustainable and economically viable fuel processing technologies.

Spontaneous grain refinement effect of rare earth zinc alloy anodes enables stable zinc batteries.

Irreversible interfacial reactions at the anodes pose a significant challenge to the long-term stability and lifespan of zinc (Zn) metal batteries, impeding their practical application as energy storage devices. The plating and stripping behavior of Zn ions on polycrystalline surfaces is inherently influenced by the microscopic structure of Zn anodes, a comprehensive understanding of which is crucial but often overlooked. Herein, commercial Zn foils were remodeled through the incorporation of cerium (Ce) elements via the 'pinning effect' during the electrodeposition process. By leveraging the electron-donating effect of Ce atoms segregated at grain boundaries (GBs), the electronic configuration of Zn is restructured to increase active sites for Zn nucleation. This facilitates continuous nucleation throughout the growth stage, leading to a high-rate instantaneous-progressive composite nucleation model that achieves a spatially uniform distribution of Zn nuclei and induces spontaneous grain refinement. Moreover, the incorporation of Ce elements elevates the site energy of GBs, mitigating detrimental parasitic reactions by enhancing the GB stability. Consequently, the remodeled ZnCe electrode exhibits highly reversible Zn plating/stripping with an accumulated capacity of up to 4.0Ah cm-2 in a Zn symmetric cell over 4000h without short-circuit behavior. Notably, a ∼0.4Ah Zn||NH4V4O10 pouch cell runs over 110 cycles with 83% capacity retention with the high-areal-loading cathode (≈20mg cm-2). This refining-grains strategy offers new insights into designing dendrite-free metal anodes in rechargeable batteries.

Synthesis, biological evaluation and in silico molecular modelling studies of chloro substituted bis-indole containing benzohydrazide analogues as potential anti-diabetic and anti-Alzheimer's agents

Fifteen bis-indolylmethane analogues were synthesized, characterized through NMR (1H, 13C) and high-resolution electron-impact mass spectrometry (HREI-MS), and tested against α-glucosidase, α-amylase, acetylcholinesterase, and butyrylcholinesterase inhibitory potentials. All analogues exhibited different inhibitory potentials, with IC50 values ranging between 7.5 ± 0.92 to 58.4 ± 0.07 μM (α-glucosidase), and 0.80 ± 0.05 to 15.30 ± 0.10 μM (α-amylase) as compared to the standard drug acarbose (IC50 = 38.45 ± 0.80 and 8.90 ± 0.10 μM). Out of fifteen analogues, nine showed an excellent inhibitory potency that was manyfold better than standard drugs. A slight increase or decrease in inhibition was observed due to substituents attached at imine site. In the case of α-amylase inhibition, two analogues such as 2 and 11, showed excellent inhibitory potential with IC50 values of 0.80 ± 0.05 and 0.90 ± 0.10 μM while all other analogues showed good potency. All analogues were also tested against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitory potentials, and they showed good potentials ranging from 1.40 ± 0.20 to 16.20 ± 0.50 μM (AChE) and 3.20 ± 0.10 to 19.60 ± 0.20 μM (BuChE) as compared to the standard drug Donepezil (IC50 = 2.16 ± 0.12 μM and 4.5 ± 0.11 μM). In the case of AChE, analogue 3 is the most potent, and in the case of BuChE, analogue 9 is the most potent among the series. The structure-activity relationship was carried out, mainly associated with the nature, number, and position and the electron-donating and electron-withdrawing effects of the substituent(s) on the phenyl ring. The binding modes as well as binding free energy for α-glucosidase and α-amylase inhibitors were determined through docking studies.

Unraveling the role of non-planarity of free base porphyrins in intermolecular hydrogen bonding interactions with phenols

Three different types of meso‑substituted freebase porphyrins (H2TTP, H2TMP and H2DDMP) with varied number and nature of electron donating groups (-CH3 and –OCH3) were synthesized. The molecular interactions of the porphyrins with different phenol derivative were explored using single crystal X-ray, NMR and their affinity by varied spectroscopic techniques. All three freebase porphyrins undergo strong intermolecular interactions with 2,4,6-trinitrophenol (TNP) and crystallized in a triclinic crystal system with iso-structural behaviour. The crystal lattices are stabilized through intermolecular hydrogen bonding interactions (N–H∙∙∙O and C–H∙∙∙O) and electrostatic interactions. Increases in the non-planarity of freebase porphyrins enhance the reactivity which results in the formation of picrate anions with 1:2 adduct formation by proton transfer process. The role of weak intermolecular interactions was analysed and quantified through Hirshfeld surface and finger print analysis. DFT studies revealed that the electron-donating effect of the methoxy group plays a major role in decreasing HOMO-LUMO gap and in-plane co-operation through the decrease in the dihedral angles. The electron density at bond critical points follows the order H2TTP.2TNP>H2TMP.2TNP>H2DDMP.2TNP. Absorption and emission studies showed that dramatic changes in the Soret and Q-band pattern and the binding constants were altered with different phenols of varied pKa. The stabilization of molecular adducts were analyzed in correlation with 1H- NMR study to reveal the involvement of the hydrogen bonding.

Synergy between electron donor and steric hindrance in Alkylated-Piperazine absorbents for efficient CO2 capture

Piperazine (PZ) and its derivatives are currently regarded as novel amine absorbents for efficient CO2 capture. However, the in-depth investigation of CO2 capture and understanding of the structure–activity relationship in PZ-based absorbents are still lacking. In this study, we conducted a systematic investigation of CO2 capture within the alkylated PZ-based absorbents. The results demonstrated that the increased alkylation degree can promote CO2 absorption by enhancing the electron donor effect of the secondary amine group in PZ. In addition, the incorporated alkyl group in PZ-based absorbent improves the CO2 desorption process by enhancing the steric hindrance effect. Particularly, the synergy between electron donor and steric hindrance effects in isopropyl alkylated-PZ (IPPZ) enables it to present enhanced cyclic capacity and remarkably low regeneration energy consumption (2.36 GJ·t−1 CO2) for CO2 capture. The present study makes a valuable contribution towards the future design and development of highly efficient absorbents for CO2 capture.

The electron-donating effect of pyridinic N sites in covalent triazine frameworks on the molecular ruthenium catalyzing CO2 hydrogenation to formate

In this study, molecular ruthenium (Ru3+) was immobilized onto pyridine-functionalized covalent triazine frameworks (CTFs) to catalyze the hydrogenation of CO2 to formate efficiently. The energy barrier for this process on N3-Ru, coordinated by both pyridinic N and triazinic-N, was found to be 29.91 kcal/mol, significantly lower than the 38.07 kcal/mol on N2-Ru, coordinated only by triazinic-N. Increasing the content of pyridine ring in the catalyst (RuCl3@CTF-1<RuCl3@CTF-2< RuCl3@CTF-3) led to a higher ratio of N3-Ru to N2-Ru. The higher the N3-Ru content, the denser the electron cloud density of Ru species, favoring Ru-H nucleophilic attack on C atoms in CO2, as confirmed by XPS. RuCl3@CTF-3, with the highest content of N3-Ru structure, exhibited the best performance (TOF=1274 h−1 at 120 °C, 6 Mpa) and the lowest apparent activation energy (Ea=36.53 KJ·mol−1) in CO2 hydrogenation, consistent with DFT calculations.

Exploring electron donor and acceptor effects: DFT analysis of ESIPT/GSIPT in 2-(oxazolinyl)-phenols for photophysical and luminophore enhancement.

Understanding excited-state intramolecular proton transfer (ESIPT) is essential for designing organic molecules to enhance photophysical and luminophore properties in the development of optoelectronic devices. In this context, an attempt has been made to understand the impact of substituents on the ESIPT process of 2-(oxazolinyl)-phenol. Electron donating (EDG: -NH2, -OCH3, and -CH3) and electron withdrawing (EWG: -Cl, -Br, -COOH, -CF3, -CN, and -NO2) substitutions have been computationally designed and screened through density functional theory (DFT) and time-dependent density-functional theory (TDDFT) calculations. Furthermore, the ground state intramolecular proton transfer and ESIPT mechanisms of these designed luminophores are explored using the transition state theory. The results reveal that molecules with EDG show higher absorption and emission peaks than molecules with EWG and also indicate that the mobility of charge carriers in 2-(oxazolinyl)-phenol derivatives is significantly influenced by substituents. We found that the EWGs decrease the reorganization energy and increase the vertical ionization potential and electron affinity values, as well as the highest occupied molecular orbital-lowest unoccupied molecular orbital gap, compared to the EDG substituted molecules. Significantly, the excited state (S1) of the keto emission (K) form shows notably larger values for the EDG substitutions. The intersystem crossing pathway efficiency weakens with reduced spin-orbit coupling matrix element in the enol form with electron-donating substituents and vice versa in the keto form during S1-T3 transitions. Our research links intramolecular proton transfers and triplet generation, making these substituted molecules appealing for optoelectronic devices. Introducing EDGs, such as -NH2, boosts the ESIPT reaction in 2-(oxazolinyl)-phenol. This study guides designing ESIPT emitters with unique photophysical properties.

In-situ fabrication of MoO2/MoxC heterojunction on rodlike carbon-coated zirconia for enhanced oxidative desulfurization of fuel oils

Electronic structure of catalysts is of great importance in redox reactions. Virtually, fabricating Mo-based heterojunction nanocomposites and elucidating their role in the nature of synergic effect between Mo compounds hold the key to promoting the electron transfer and eventually improving oxidative desulfurization (ODS) performances. Herein, the molybdenum dioxide/molybdenum carbides (MoO2/MoxC) heterojunction was in situ dispersedly immobilized on a rodlike N-doped carbon (NC)-coated zirconia (ZrO2) via a facile annealing route employing phosphomolybdic acid (PMo12)-loaded Zr(IV) porphyrinic metal–organic framework (MOF-545) (i.e. PMo12@MOF-545) as a precursor. The optimized catalyst (MoO2/MoxC@NC@ZrO2) exhibits outstanding oxidative desulfurization (ODS) activities for fuel oil with sulfur content in a wide range of 200～4000 ppm. It is indicated that the extraordinary ODS activity of MoO2/MoxC@NC@ZrO2 significantly stems from the accelerated electron transfer by the MoO2/MoxC heterojunction, the strong electron-donating effect of NC layer, and abundant active sites from the extremely dispersed Mo compounds realized by both NC and ZrO2. The ODS reaction is elucidated by the •OH radical mechanism. Moreover, MoO2/MoxC@NC@ZrO2 shows excellent stability, and the sulfur removal could remain over 96.5 % after thirteen cycles. This work not only opens up a new avenue for in situ integrating Mo-based heterojunctions, but also manifests a promising potential for practical ODS process.

A Fully Methylated Cyclic Ether Solvent Enables Graphite Anode Cycling at Low Temperatures.

Graphite anode suffers from great capacity loss and larger cell polarization under low-temperature conditions in lithium-ion batteries (LIBs), which are mainly caused by the high energy barrier for the Li+ desolvation process and sluggish Li+ transfer rate across the solid electrolyte interface (SEI). Regulating an electrolyte with an anion-dominated solvation structure could synchronously stabilize the interface and boost the reaction kinetics of the graphite anode. Herein, a highly ionic conductive electrolyte consisting of a fully methylated cyclic ether solvent of 2,2,4,4,5,5-hexamethyl-1,3-dioxolane (HMD) and fluoroethylene carbonate (FEC) cosolvent was designed. The high electron-donating effect and steric hindrance of -(CH3)2 in HMD endow the HMD-based electrolyte with high ionic conductivity but lower coordination numbers with Li+, and an anion-dominated solvation structure was formed. Such configuration can accelerate the desolvation process and induce the forming of a LiF-rich SEI film on the anode, avoiding the solvent coembedding into graphite and enhancing the ion migration rate under low temperatures. The assembled Li||graphite cell with the tame electrolyte outperformed the conventional carbonates-based cell, showing 93.8% capacity retention after 227 cycles for the DF-based cell compared to 64.7% after 150 cycles. It also exhibited a prolonged cycle life for 200 rounds with 81% capacity retention under -20 °C. Therefore, this work offers a valuable thought for solvent design and provides approaches to electrolyte design for low-temperature LIBs.

Fine-Tuning Electron-Donor Capability in the Basic Anion of Poly(ionic liquid) Frameworks for Revolutionizing Catalytic Synthesis of Ethyl Methyl Carbonate with Both Ultrahigh Catalytic Activity and Selectivity.

Ethyl methyl carbonate (EMC) is a crucial solvent extensively utilized in lithium-ion battery electrolytes; the transesterification of dimethyl carbonate (DMC) with ethanol is a pivotal reaction for EMC production. However, this reaction faces challenges due to the trade-off between catalytic activity and selectivity from the basic catalysts. In this issue, we report an innovative strategy through fine-tuning the electron-donor capability of the basic phenolate anion ([PhO]) in a novel poly(ionic liquid) (PIL) framework, as synthesized via an alkylation reaction between 1,3,5-tris(bromomethyl)benzene, biphenyldiimidazole, and N,N'-carbonyldiimidazole (CDI) to trigger targeted basicity that can directionally catalyze the transesterification of DMC with ethanol, so as to achieve both ultrahigh catalytic activity and selectivity toward EMC. By varying the substituent groups with electron-withdrawing and electron-donating effects on the phenolate anion, the PILs show expected changes in the catalytic performance, following well with the trend of charge density on these substituted phenolate anions. The optimized catalyst [CPIL-CDI][MeOPhO], induced by p-methoxyphenolate anions, allows an extraordinary EMC yield of 72.19% and an EMC selectivity of 91.48% under mild conditions without any process intensifications, suppressing all of the reported catalysts reported to date. Outcomes and approaches shown in this work have the potential to expedite the systematic design of cations and anions within PILs for industrial-scale EMC production through environmentally friendly transesterification processes.

Total hydrogenation of furfural on Pd/COFs under mild conditions

Total hydrogenation of furfural (FAL) is an efficient way to produce the industrially important tetrahydrofurfuryl alcohol (THFOL). However, it is a challenge to obtain highly selective catalysts for this transformation especially under mild reaction conditions. Herein, we report that the β-ketoenamine-linked covalent organic framework (TpBD COF) supported ultrafine Pd nanoparticles exhibit significantly enhanced selectivity for THFOL compared to Pd/C (95% vs. 82 %) at almost full FAL conversion. This heightened selectivity is attributed to the increased electronic density on the Pd surface, resulting from the electron-donating effect of pendant groups in the TpBD COF. Moreover, kinetic investigations reveal that the activity of total FAL hydrogenation on Pd surface is linked to the rate-determining step in its first C = O hydrogenation process. Additionally, Pd/TpBD COF could catalyse various other bio-based furanic compounds to the corresponding furan ring saturated products in high yields. This work provides guidance for the rational design catalysts to improve its tandem hydrogenation efficiency.

“Electron-donating effect” of element S and “electron-accepting effect” of element N in regulating the interfacial contact electrification

“Electron-donating effect” of element S and “electron-accepting effect” of element N in regulating the interfacial contact electrification

Understanding support effects on Rh2P catalyzed styrene hydroformylation by combining characterizations and kinetics

Styrene hydroformylation over Rh2P loaded on different oxides was compared to investigate support effects on catalytic performance. The electron density of Rh was probed by CO-DRIFTS, and the acid-base properties of the catalysts were detected by NH3- and CO2-TPD. Rh2P had higher electron density when loaded on basic supports, and n-type semiconductor showed additional electron donation effects compared to isolators. A kinetics model was established to identify hydrogen addition as the rate-determining step, and the changes in rate constant and adsorption equilibrium with different supports were compared. Electron donation from the supports was found to promote the activity of Rh2P via weakening styrene and aldehyde adsorption and facilitating hydrogen addition. The advantage of using CeO2 (i.e., basic oxide with n-type semiconductivity) as the support was suggested.

Simulation study on functional group-modified Ni-MOF-74 for CH4/N2 adsorption separation.

This study employs grand canonical Monte Carlo (GCMC) simulations to investigate the impact of functional group modifications (CH3, OH, NH2, and OLi) on the adsorption performance of CH4/N2 on Ni-MOF-74. The results revealed that functional group modifications significantly increased the adsorption capacity of Ni-MOF-74 for both CH4 and N2. The packed methyl groups in CH3-Ni-MOF-74 create an environment conducive to CH4, leading to the highest CH4 adsorption capacity. The electrostatic potential distribution indicates that the strong electron-donating effect introduced by the alkali metal Li results in the highest electrostatic potential gradient in Li-O-Ni-MOF-74, leading to the strongest adsorption of N2, this is unfavorable for CH4/N2 separation. At 1500 kPa the selectivity order of adsorbents for mixed gases was as follows: CH3-Ni-MOF-74 > NH2-Ni-MOF-74 > OH-Ni-MOF-74 > Ni-MOF-74 > Li-O-Ni-MOF-74. This study highlights that CH3-Ni-MOF-74 possesses optimal CH4 selectivity and adsorption performance. Given the current lack of research on functionalized MOF-74 for the separation of CH4 and N2, the findings of this study will serve as a theoretical guide and provide references for the applications of CH4 adsorption and CH4/N2 separation.

Electrocatalytically enhanced Cu(II)/peroxymonosulfate (PMS) oxidation: Focus on electrically-induced sustained Cu(II)/Cu(I)/Cu(III) cycling and suppression of singlet oxygen (1O2) production

Numerous azo dyes are discharged into industrial wastewater annually, posing significant threats to ecology and human health. In this study, an applied electric field was implemented in a trace copper-activated peroxymonosulfate system (EC/Cu(II)/PMS), achieving high removal efficiency (95.40 %) of Congo red (CR). The electron-donating effect of the cathode greatly enhanced the redox cycling of Cu(II)/Cu(I). Almost complete activation of PMS occurred during the entire reaction with an electrical consumption of merely 0.85 kWh/m3. Using electron paramagnetic resonance (EPR), quenching experiments, and chemical probes, the reactive substance that dominate CR removal, including Cu(III), sulfate radical (SO4•−), hydroxyl radical (HO∙), and singlet oxygen (1O2), were investigated. Cu(III) was identified as the main reactive substance, contributing over 90 %, and was primarily formed through double electron transfer of Cu(I). HO∙ can emerge as a secondary oxide of Cu(III). SO4•− originated mainly from the electroactivation of PMS. It was noted that 1O2 can be physically quenched by water, and thus 1O2 was considered as a side reaction product of PMS. Applying an electric field lowered the overall production of 1O2 and markedly mitigated the inefficient consumption of PMS. Moreover, the degradation pathways proposed for CR, based on mass spectrometry analysis, were in agreement with the predictions made by density functional theory (DFT). The toxicological characteristics of both CR and its intermediates were comprehensively analyzed as well. The study presents a straightforward and efficient strategy for PMS activation with versatile application potential for dye wastewater treatment.

Carbon modified active pairs of Co-Co2C for CO2 hydrogenation to alcohols

The transformation process of CO2-to-alcohols can achieve the reduction in emissions of carbon dioxide and hydrogen storage, considered to be the up-and-coming way to realize the utilization of CO2. Co-based catalysts are promising, where Co0/Coδ+ is the critical active pair. The challenge is how to construct and tailor the active pair of Co0/Coδ+, to which a new scheme has been proposed in this work. Dual active sites of Co-Co2C were constructed and tailored by the carbon deposition via catalytic decomposition of methane reaction in this scheme. The formation of Co2C species promoted the non-dissociation of COx intermediates, which greatly contributed to the synthesis of alcohols. Not only the state of the Co active component changed with the addition of carbon species, but its own electron-donating effect increased the activation rate of CO2. The catalyst exhibited a CO2 turnover frequency of 7.4 × 10−3 s−1, 16.9 C-mol% and 29.5 C-mol% for ethanol and methanol selectivity at 270 °C and 3 MPa, respectively. This study provides a reference for catalyst design with the help of carbon species to modulate the state of active components.

Chemical control of excited-state reactivity of the anionic green fluorescent protein chromophore.

Controlling excited-state reactivity is a long-standing challenge in photochemistry, as a desired pathway may be inaccessible or compete with other unwanted channels. An important example is internal conversion of the anionic green fluorescent protein (GFP) chromophore where non-selective progress along two competing torsional modes (P: phenolate and I: imidazolinone) impairs and enables Z-to-E photoisomerization, respectively. Developing strategies to promote photoisomerization could drive new areas of applications of GFP-like proteins. Motivated by the charge-transfer dichotomy of the torsional modes, we explore chemical substitution on the P-ring of the chromophore as a way to control excited-state pathways and improve photoisomerization. As demonstrated by methoxylation, selective P-twisting appears difficult to achieve because the electron-donating potential effects of the substituents are counteracted by inertial effects that directly retard the motion. Conversely, these effects act in concert to promote I-twisting when introducing electron-withdrawing groups. Specifically, 2,3,5-trifluorination leads to both pathway selectivity and a more direct approach to the I-twisted intersection which, in turn, doubles the photoisomerization quantum yield. Our results suggest P-ring engineering as an effective approach to boost photoisomerization of the anionic GFP chromophore.

Artificial Surface Electron Network Prompted Energy Band Structure Tuning: Boosting Solar-to-Hydrogen Evolution Performance.

The energy gap and conduction band position of catalysts play crucial roles in solar-to-hydrogen (STH) transformation technology. Unfortunately, although an increase in the conduction band position can effectively promote the photoreduction capacity of the photocatalyst, it will inevitably widen the band gap, thus reducing the light-absorption scale. It seems that there is a contradiction between the reduction of band gap and the improvement of conduction band position, which is that "You can't have your cake and eat it too." Herein, an ultrasimple molecular adsorption strategy was engineered by adsorbing hydrazine hydrate on the surface of TiO2. The theoretical and experimental results indicated that the strong electron-donating effect of amino groups in hydrazine hydrate can promote the redistribution of photogenerated electrons and form surface electron networks on the surface of TiO2 photocatalysts, which can bend the conduction band upward and significantly improve its photoreduction ability. Besides, the adsorption of -NH2 can narrow the band gap width of TiO2 and promote the separation efficiency of photogenerated carriers. More interestingly, it can also effectively enhance the adsorption of H2O and H+, thus greatly elevating the STH efficiency. The STH rate of the as-prepared T-N-3 can be increased by ≈530%. This work sheds light on a new approach for resolving the contradiction between photoreduction and light absorption capabilities to effectively enhance photocatalytic performance.

Boosted hydrogen evolution kinetics of heteroatom-doped carbons with isolated Zn as an accelerant

Carbon-based single-atom catalysts, a promising candidate in electrocatalysis, offer insights into electron-donating effects of metal center on adjacent atoms. Herein, we present a practical strategy to rationally design a model catalyst with a single zinc (Zn) atom coordinated with nitrogen and sulfur atoms in a multilevel carbon matrix. The Zn site exhibits an atomic interface configuration of ZnN4S1, where Zn's electron injection effect enables thermal-neutral hydrogen adsorption on neighboring atoms, pushing the activity boundaries of carbon electrocatalysts toward electrochemical hydrogen evolution to an unprecedented level. Experimental and theoretical analyses confirm the low-barrier Volmer-Tafel mechanism of proton reduction, while the multishell hollow structures facilitate the hydrogen evolution even at high current intensities. This work provides insights for understanding the actual active species during hydrogen evolution reaction and paves the way for designing high-performance electrocatalysts.