查看更多>>摘要：? 2022 Elsevier B.V.Maximumly increasing the number of active sites is crucial to improve the H2-evolution efficiency of cocatalyst. Herein, a rich-active-site regulation strategy by the synergism of unsaturated selenium enrichment and amorphization is developed to precisely construct unsaturated selenium-enriched MoSe2+x amorphous nanoclusters onto the TiO2 via a mild photoinduced co-reduction route by using MoCl5 and dibenzyl diselenide as the precursors. The resulting a-MoSe2+x exposes more unsaturated Se atoms (46.5%) because of its unsaturated Se-enriched configuration, highly irregular arrangement, and ultrasmall size (0.3 ?1 nm). Photocatalytic tests show that the a-MoSe2+x/TiO2(3 wt%) achieves an optimal H2-evolution rate (4984.46 μmol h?1 g?1, AQE = 23.90%), with the 4.51-fold enhancement relative to that of c-MoSe2/TiO2. Hence, a rich unsaturated Se-mediated H2-evolution mechanism is proposed, namely, the abundant unsaturated Se atoms as the active sites can not only provide sufficient proton-adsorption-centers to enrich H+, but also present an outstanding catalytic efficiency to fleetly convert H+ to H2.
查看更多>>摘要：? 2022Photocatalytic pure water splitting using particulate photocatalyst is usually restricted by the extremely slow reaction kinetics. Herein, we demonstrated a novel Z-scheme heterojunction, composed of a phosphatized p-type gallium indium zinc oxynitride (GIZON-P) and a n-type g-C3N4 (CN). Results show that phosphorization could reduce hole concentration within p-type GIZON, resulting in the transition of Z-scheme band structure into type-Ⅱ style. This transformation leads to a completely changed reaction mechanism, i.e., from a two-electron H2/H2O2 production to a four-electron H2/O2 generation. Although this four-electron pathway is dynamically unfavorable, the rapid charge separation by the type-II band arrangement together with thin InP layer at the surface of GIZON-P could remarkably accelerate the rate-limited O2-evolution process. The phosphatized composite presents an excellent photocatalytic performance, with a H2/O2 rate of 1340/643 μmol h g. The gained quantum yield of 12.6% at 430 nm is among the best results in photocatalytic pure water splitting.
查看更多>>摘要：? 2022 Elsevier B.V.The unsaturated edge S in the cocatalyst plays an important role in the enrichment of both protons and electrons during the photocatalytic hydrogen evolution process. However, a mild and simple strategy for effectively exposing edge S is still a significant challenge. Herein, amorphous nickel sulfide (NiSx) as an efficient cocatalyst was decorated on the cubic phase CdS surface, which were confined growth inside hydrophilic chitosan hydrogel beads (CHB@CdS-NiSx) for efficient and durable photocatalytic H2 evolution. The optimal CHB@CdS-0.02NiSx achieved a photocatalytic activity of 11.88 mmol/h/g and displayed ultra-long stability of 60 h. NiSx could effectively accelerate the electron migration from CdS to NiSx in composite photocatalyst and provide abundant unsaturated edge active S as H2-evolution sites. Further density functional theory (DFT) calculation revealed that NiSx lowered activation energy for H2O dissociation to boost the local proton concentration, thereby facilitating the activity of H2 evolution. This study highlights the significance of amorphization strategy for consciously modulating edge sulfur of transition metal sulfide cocatalysts to improve the photocatalytic performance.
查看更多>>摘要：? 2022 Elsevier B.V.The development of nanostructured electrodes of solid oxide cells is largely hindered by the high temperature sintering process and limited in the loading and choices of catalytic phases. Here, a nanostructured multi-phase air electrode is fabricated via facile combination of Gd0.2Ce0.8O1.9 (GDC) decorated PrBa0.8Ca0.2Co2O5+δ (PBCC) and direct assembly approach. The highly flexible decoration process and the in situ formation of multi-phases lead to the formation of intertwined core-shell type nanostructures with intimate electrode/electrolyte interface. A cell with a 40 wt% GDC decorated PBCC electrode achieves a peak power density of 1.74 W cm?2 at 750 °C and an electrolysis current density of 1.77 A cm?2 at 1.3 V with excellent durability for 200 h. The combined decoration and direct assembly approach provides a unique and general pathway to develop a new class of nanostructured air electrodes for efficient and durable solid oxide cells.
查看更多>>摘要：? 2022 Elsevier B.V.Reactive oxygen species (ROSs) quenching by inorganic anions and natural organic matter (NOM) restricts efficiency upgradation of advanced oxidation process. Here a novel ‘4H’ carbon polyhedral catalyst featuring hollow structure, high-density single-atom cobalt sites, high adsorbability and high conductivity is designed to activate peroxymonosulfate (PMS) for bisphenol A (BPA) degradation. 91.62% of BPA is removed within 15 s, and the catalyst-dose-normalized kinetic rate constant reaches 92.92 L min?1 g?1, outdistancing reported values. Meanwhile, the composite demonstrates excellent anti-interference ability against anions and NOM. Moreover, the catalyst-loaded column reactor realizes BPA zero discharge for impressive 12.19 days. Experimental and theoretical evidences reveal that PMS bound on the single-atom cobalt site excites radial micro-electric field on the carbon support to drive electron extraction from co-adsorbed BPA, which fundamentally eliminates ROSs quenching and guarantees robust pollutant oxidation. This work can guide the ‘4H’ catalyst design and refresh the atomic-level understanding of electron-transfer pathway.
查看更多>>摘要：? 2022 Elsevier B.V.Single-atom catalysts (SAC) stabilized by nitrogen in carbon support are promising candidates for oxygen reduction reaction (ORR). However, conventional preparation methods usually lead to encapsulation of metallic centers in matrix and thus the utilization efficiency (UE) is underexploited. Herein, we report a novel strategy to prepare an Fe-SAC with all Fe atoms anchored on the surface of carbon nanospheres, which exhibited an extraordinary UE of 80% for ORR. This efficiency was achieved by coating polydopamine spheres with silica, followed by the pyrolysis of their blend with FeCl3. During thermal treatment, Fe migrates across the silica shell by atomic exchange with silicon, which inhibits the aggregation of Fe and allows Fe atoms to anchor on the surface. As such, it showed excellent ORR activity at a low Fe content. Zn-air batteries assembled using this catalyst showed a peak power density of 113 mW cm?2 and specific capacity of 710 mAh gZn?1.
查看更多>>摘要：? 2022We report electrocatalytic decarboxylation (ECDX) of valeric acid into paraffins, olefins, and alcohols via (non-)Kolbe electrolysis on electrodes with RuO2 and Pt nanoparticles (NPs) as a greener alternative to thermocatalytic decarboxylation. The turnover frequency of ECDX increases, while the specific activity peaks as RuO2 NP size increases. These opposing trends make the particle size of ～ 12 nm the optimum size for ECDX on RuO2. Bulk Pt was active for ECDX, while Pt NPs were only active for the oxygen evolution reaction under our conditions. ECDX current efficiency remained constant in the studied potential range on RuO2 NPs. Esterification was the favored reaction at 2.5 V vs. RHE; however, Kolbe electrolysis was the favored reaction at the expense of the esterification at 4.5 V vs. RHE. This work highlights the performance of nanostructured materials as an alternative to bulk materials as anodes for oxidative upgrading of carboxylic acids.
查看更多>>摘要：? 2022 Elsevier B.V.Metal single atoms often exhibit unique selectivity with maximized atom efficiency. However, they are usually generated at low metal loadings and susceptible to severe reaction conditions resulting in metal sintering, which can be overcome by a new synthesis method offering strong metal–support interaction. Here we show a great potential of one-pot solvent deficient precipitation (SDP) affording mesoporous Pt–Al2O3 (MPtA). This method is unique in creating Pt single atoms and clusters at up to 3 wt% loading because of the restricted Pt mobility by contiguous Al2O3 particles. The MPtA of 3 wt% Pt, representing ensemble species of single atoms and clusters, is more active and stable than the general impregnated catalyst comprised of Pt nanoparticles. Moreover, it successfully accomplishes reversible H2 release and charge of commercial benzyltoluene-type hydrogen carriers. The size and activity of Pt species is readily tuned in the MPtA, which will exert remarkable impacts on catalysis.
查看更多>>摘要：? 2022 Elsevier B.V.Electrochemical hydrogenation (ECH) is a particularly important and environmentally friendly approach to obtain biomass-based fuels and high value-added fine chemicals without using external hydrogen. Herein, we reported a highly efficient and selective ECH of furfural (FF) into furfuryl alcohol (FA) with Cu-based electrocatalyst in aqueous alkaline media. Under the optimal conditions, FA selectivity close to 100% with 99% FF conversion and total Faradaic efficiency above 95% were obtained with the electrocatalyst. Mechanism investigation suggests an ECH mechanism for FA formation, which is highly potential-dependent to FA selectivity, requiring low and well-matched concentrations between active hydrogen (Hads) species and FA radical on the Cu surface. Moreover, the electrocatalyst shows an excellent stability and recyclability during the eight-time consecutive recycling experiments, yielding a total amount of 1011 mg FA. This work thus highlights an important guidance for electrocatalytic upgrading of biomass-based platform molecules in an environmentally friendly way.
查看更多>>摘要：? 2022 Elsevier B.V.Current sunlight-powered H2 production that employ carbonized polymer dots (CPDs)-graphitic carbon nitride (g-C3N4) systems has made significant progress. However, we still have a limited understanding of the mechanism by which CPDs contribute to the phtocatalytic efficiency. Surface molecule 1,2,3,5-tetrahydro-5-oxo-imidazo[1,2-α]pyridine-7-carboxylic acid (IPCA) has been verified to largely impact the photophysical properties of CPDs. Here, we report the design of g-C3N4, IPCA-g-C3N4 and CPDs-g-C3N4 catalysts to uncover the critical role of IPCA. The photocatalytic H2 production rates of g-C3N4 were improved by the hybridization with IPCA and CPDs (1172 ± 39; 2150 ± 92 vs. 828 ± 121 μmol g?1 h?1, respectively). The DFT calculations further unraveled that electron transfer pathway in ICPA-CN@H3O+ followed ICPA -> g-C3N4 -> H3O+ procedure. The results indicate that IPCA on CPDs is conducive to extending the light-responsive range, redistributing of photoinduced electron-hole pairs, increasing the electron density of g-C3N4, and thus improving H2 generation rates.
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