Strong Second-Harmonic Generation Induced by a Triphenylamine-Based Bismuth-Organic Framework for Photocatalytic Activity Enhancement.

Taking advantage of the well-defined geometry of metal centers and highly directional metal-ligand coordination bonds, metal-organic frameworks (MOFs) have emerged as promising candidates for nonlinear optical (NLO) materials. In this work, taking a photoresponsive carboxylate triphenylamine derivative as an organic ligand, a bismuth-based MOF, Bi-NBC, NBC = 4',4‴,4‴″-nitrilotris(([1,1'-biphenyl]-4-carboxylic acid)) is obtained. Structure determination reveals that it is a potential NLO material derived from its noncentrosymmetric structure, which is finally confirmed by its rarely strong second harmonic generation (SHG) effect. Theoretical calculations reveal that the potential difference around Bi atoms is large; therefore, it leads to a strong local built-in electric field, which greatly facilitates the charge separation and transfer and finally improves the photocatalytic performance. Our results provide a reference for the exploration of MOFs with NLO properties.

Asymmetric Cu(I)─W Dual-Atomic Sites Enable C─C Coupling for Selective Photocatalytic CO2 Reduction to C2H4.

Solar-driven CO2 reduction into value-added C2+ chemical fuels, such as C2H4, is promising in meeting the carbon-neutral future, yet the performance is usually hindered by the high energy barrier of the C─C coupling process. Here, an efficient and stabilized Cu(I) single atoms-modified W18O49 nanowires (Cu1/W18O49) photocatalyst with asymmetric Cu─W dual sites is reported for selective photocatalytic CO2 reduction to C2H4. The interconversion between W(V) and W(VI) in W18O49 ensures the stability of Cu(I) during the photocatalytic process. Under light irradiation, the optimal Cu1/W18O49 (3.6-Cu1/W18O49) catalyst exhibits concurrent high activity and selectivity toward C2H4 production, reaching a corresponding yield rate of 4.9 µmol g-1 h-1 and selectivity as high as 72.8%, respectively. Combined in situ spectroscopies and computational calculations reveal that Cu(I) single atoms stabilize the *CO intermediate, and the asymmetric Cu─W dual sites effectively reduce the energy barrier for the C─C coupling of two neighboring CO intermediates, enabling the highly selective C2H4 generation from CO2 photoreduction. This work demonstrates leveraging stabilized atomically-dispersed Cu(I) in asymmetric dual-sites for selective CO2-to-C2H4 conversion and can provide new insight into photocatalytic CO2 reduction to other targeted C2+ products through rational construction of active sites for C─C coupling.

Hydrogen Bonds Induced Ultralong Stability of Conductive π-d Conjugated FeCo3(DDA)2 with High OER Activity.

Conductive π-d conjugated metal-organic frameworks (MOFs) have attracted wide concerns in electrocatalysis due to their intrinsic high conductivity. However, the poor electrocatalytic stability is still a major problem that hinders the practical application of MOFs. Herein, a novel approach to enhancing the stability of MOF-based electrocatalyst, namely, the introduction of hydrogen bonds (H-bonds), is reported. Impressively, the π-d conjugated MOF FeCo3(DDA)2 (DDA = 1,5-diamino-4,8-dihydroxy-9,10-anthraceneedione) exhibits ultrahigh oxygen evolution reaction (OER) stability (up to 2000 h). The experimental studies demonstrate that the presence of H-bonds in FeCo3(DDA)2 is responsible for its ultrahigh OER stability. Besides that, FeCo3(DDA)2 also displays a prominent OER activity (an overpotential of 260 mV vs reversible hydrogen electrode (RHE) at a current density of 10 mA cm-2 and a Tafel slope of 46.86 mV dec-1). Density functional theory (DFT) calculations further indicate that the synergistic effect of the Fe and Co sites in FeCo3(DDA)2 contributes to its prominent OER performance. This work provides a new avenue of boosting the electrocatalytic stability of conductive π-d conjugated MOFs.

Composite of formamidinium lead bromide perovskite FAPbBr3 with reduced graphene oxide (rGO) for efficient H2 evolution from HBr splitting.

Solar hydrobromic acid (HBr) splitting using perovskite photocatalysts provides an attractive avenue to store solar energy into hydrogen (H2) and bromine (Br2), while an efficient photocatalytic system is still demanded. As for the semiconductor photocatalyst, formamidinium perovskites show some superiorities in structural stability, light adsorption and charge dynamics compared to their methylammonium counterparts, which are fitter for the photocatalysis process. Herein, the composite of formamidinium lead bromide perovskite (FAPbBr3) with reduced graphene oxide (rGO) is prepared using a facile photoreduction method. Under simulated sunlight irradiation (AM1.5G, 100 mW cm-2), this FAPbBr3/rGO composite (100 mg) demonstrates a noteworthy enhancement in photocatalytic H2 evolution activity of 386.7 µmol h-1, and it exhibits a notable stability with no significant decrease after 50 h of repeated tests. The single particle PL (photoluminescence) microscope is employed to study the charge dynamics, revealing that rGO in the composite effectively promotes the carrier separation. This work provides a highly efficient and stable photocatalyst for HBr splitting, and offers an effective modification strategy on lead bromide perovskites.

Pd-Decorated Cu2O-Ag Catalyst Promoting CO2 Electroreduction to C2H4 by Optimizing CO Intermediate Adsorption and Hydrogenation.

Electrocatalytic CO2 reduction reaction (CO2RR) to high value-added products, such as ethylene (C2H4), offers a promising approach to achieve carbon neutrality. Although recent studies have reported that a tandem catalyst (for example, Cu-Ag systems) exhibits advantage in C2H4 production, its practical application is largely inhibited by the following: (1) a traditional tandem catalyst cannot effectively stabilize the *CO intermediate, resulting in sluggish C-C coupling, and (2) inadequate H2O activation ability hinders the hydrogenation of intermediates. To break through the above bottleneck, herein, palladium (Pd) was introduced into Cu2O-Ag, a typical conventional tandem catalyst, to construct a Cu2O-Pd-Ag ternary catalyst. Extensive experiment and density functional theory calculation prove that Pd can efficiently stabilize the *CO intermediate and promote the H2O activation, which contributes to the C-C coupling and intermediate hydrogenation, the key steps in the conversion of CO2 to C2H4. Beneficial to the efficient synergy of Cu2O, Pd, and Ag, the optimal Cu2O-Pd-Ag ternary catalyst achieves CO2RR toward C2H4 with a faradaic efficiency of 63.2% at -1.2 VRHE, which is higher than that achieved by Cu2O-Ag and most of other reported catalysts. This work is a fruitful exploration of a rare ternary catalyst, providing a new route for constructing an efficient CO2RR electrocatalyst.

Enhanced Charge Transfer Process and Photocatalytic Activity over a Phosphonate-based MOF via Amorphization Strategy.

Recently, amorphous materials have gained great attention as an emerging kind of functional material, and their characteristics such as isotropy, absence of grain boundaries, and abundant defects are very likely to outrun the disadvantages of crystalline counterparts, such as low conductivity, and ultimately lead to improved charge transfer efficiency. Herein, we investigated the effect of amorphization on the charge transfer process and photocatalytic performance with a phosphonate-based metal-organic framework (FePPA) as the research object. Comprehensive experimental results suggest that compared to crystalline FePPA, amorphous FePPA has more distorted metal nodes, which affects the electron distribution and consequently improves the photogenerated charge separation efficiency. Meanwhile, the distorted metal nodes in amorphous FePPA also greatly promote the adsorption and activation of O2. Hence, amorphous FePPA exhibits a better performance of photocatalytic C(sp3)-H bond activation for selective oxidation of toluene to benzaldehyde. This work illustrates the advantages of amorphous MOFs in the charge transfer process, which is conducive to the further development of high performance MOFs-based photocatalysts.

Revealing the Lattice Carbonate Mediated Mechanism in Cu2(OH)2CO3 for Electrocatalytic Reduction of CO2 to C2H4.

Understanding the CO2 transformation mechanism on materials is essential for the design of efficient electrocatalysts for CO2 reduction. In aconventional adsorbate evolution mechanism (AEM), the catalysts encounter multiple high-energy barrier steps, especially CO2 activation, limiting the activity and selectivity. Here, lattice carbonate from Cu2(OH)2CO3 is revealed to be a mediator between CO2 molecules and catalyst during CO2 electroreduction by a 13C isotope labeling method, which can bypass the high energy barrier of CO2 activation and strongly enhance the performance. With the lattice carbonate mediated mechanism (LCMM), the Cu2(OH)2CO3 electrode exhibited ten-fold faradaic efficiency and 15-fold current density for ethylene production than the Cu2O electrode with AEM at a low overpotential. Theoretical calculations and in situ Raman spectroscopy results show that symmetric vibration of carbonate is precisely enhanced on the catalyst surface with LCMM, leading to faster electron transfer, and lower energy barriers of CO2 activation and carbon-carbon coupling. This work provides a route to develop efficient electrocatalysts for CO2 reduction based on lattice-mediated mechanism.

Polar Aromatic Two-dimensional Dion-Jacobson Halide Perovskites for Efficient Photocatalytic H2 Evolution.

Polar materials with spontaneous polarization (Ps) have emerged as highly promising photocatalysts for efficient photocatalytic H2 evolution owing to the Ps-enhanced photogenerated carrier separation. However, traditional inorganic polar materials often suffer from limitations such as wide band gaps and poor carrier transport, which hinders their photocatalytic H2 evolution efficiency. Here, we rationally synthesized a series of isostructural two-dimensional (2D) aromatic Dion-Jacobson (DJ) perovskites, namely (2-(2-Aminoethyl)pyridinium)PbI4 (2-APDPI), (3-(2-Aminoethyl)pyridinium)PbI4 (3-APDPI), and (4-(2-Aminoethyl)pyridinium)PbI4 (4-APDPI), where 2-APDPI and 4-APDPI crystalize in polar space groups with piezoelectric constants (d33) of approximately 40 pm V-1 and 3-APDPI adopts a centrosymmetric structure. Strikingly, owing to the Ps-facilitated separation of photogenerated carriers, polar 2-APDPI and 4-APDPI exhibit a 3.9- and 2.8-fold increase, respectively, in photocatalytic H2 evolution compared to the centrosymmetric 3-APDPI. As a pioneering study, this work provides an efficient approach for exploring new polar photocatalysts and highlights their potential in promoting photocatalytic H2 evolution.

Unveiling pH-Dependent Adsorption Strength of *CO2 - Intermediate over High-Density Sn Single Atom Catalyst for Acidic CO2-to-HCOOH Electroreduction.

The acidic electrochemical CO2 reduction reaction (CO2RR) for direct formic acid (HCOOH) production holds promise in meeting the carbon-neutral target, yet its performance is hindered by the competing hydrogen evolution reaction (HER). Understanding the adsorption strength of the key intermediates in acidic electrolyte is indispensable to favor CO2RR over HER. In this work, high-density Sn single atom catalysts (SACs) were prepared and used as catalyst, to reveal the pH-dependent adsorption strength and coverage of *CO2 - intermediatethat enables enhanced acidic CO2RR towards direct HCOOH production. At pH=3, Sn SACs could deliver a high Faradaic efficiency (90.8 %) of HCOOH formation and a corresponding partial current density up to -178.5 mA cm-2. The detailed in situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopic studies reveal that a favorable alkaline microenvironment for CO2RR to HCOOH is formed near the surface of Sn SACs, even in the acidic electrolyte. More importantly, the pH-dependent adsorption strength of *CO2 - intermediate is unravelled over the Sn SACs, which in turn affects the competition between HER and CO2RR in acidic electrolyte.

Semimetallic Bismuthene with Edge-Rich Dangling Bonds: Broad-Spectrum-Driven and Edge-Confined Electron Enhancement Boosting CO2 Hydrogenation Reduction.

Broad-spectrum-driven high-performance artificial photosynthesis is quite challenging. Herein, atomically ultrathin bismuthene with semimetallic properties is designed and demonstrated for broad-spectrum (ultraviolet-visible-near infrared light) (UV-vis-NIR)-driven photocatalytic CO2 hydrogenation. The trap states in the bandgap produced by edge dangling bonds prolong the lifetime of the photogenerated electrons from 90 ps in bulk Bi to 1650 ps in bismuthine, and excited-state electrons are enriched at the edge of bismuthine. The edge dangling bonds of bismuthene as the active sites for adsorption/activation of CO2 increase the hybridization ability of the Bi 6p orbital and O 2p orbital to significantly reduce the catalytic reaction energy barrier and promote the formation of C─H bonds until the generation of CH4. Under λ ≥ 400 nm and λ ≥ 550 nm irradiation, the utilization ratios of photogenerated electron reduction CO2 hydrogenation to CO and CH4 for bismuthene are 58.24 and 300.50 times higher than those of bulk Bi, respectively. Moreover, bismuthene can extend the CO2 hydrogenation reaction to the near-infrared region (λ ≥ 700 nm). This pioneering work employs the single semimetal element as an artificial photosynthetic catalyst to produce a broad spectral response.

A Conductive 3D Dual-Metal π-d Conjugated Metal-Organic Framework Fe3(HITP)2/bpm@Co for Highly Efficient Oxygen Evolution Reaction.

Although 2D π-d conjugated metal-organic frameworks (MOFs) exhibit high in-plane conductivity, the closely stacked layers result in low specific surface area and difficulty in mass transfer and diffusion. Hence, a conductive 3D MOF Fe3(HITP)2/bpm@Co (HITP = 2,3,6,7,10,11-hexaiminotriphenylene) is reported through inserting bpm (4,4'-bipyrimidine) ligands and Co2+ into the interlayers of 2D MOF Fe3(HITP)2. Compared to 2D Fe3(HITP)2 (37.23 m2 g-1), 3D Fe3(HITP)2/bpm@Co displays a huge improvement in the specific surface area (373.82 m2 g-1). Furthermore, the combined experimental and density functional theory (DFT) theoretical calculations demonstrate the metallic behavior of Fe3(HITP)2/bpm@Co, which will benefit to the electrocatalytic activity of it. Impressively, Fe3(HITP)2/bpm@Co exhibits prominent and stable oxygen evolution reaction (OER) performance (an overpotential of 299 mV vs RHE at a current density of 10 mA cm-2 and a Tafel slope of 37.14 mV dec-1), which is superior to 2D Fe3(HITP)2 and comparable to commercial IrO2. DFT theoretical calculation reveals that the combined action of the Fe and Co sites in Fe3(HITP)2/bpm@Co is responsible for the enhanced electrocatalytic activity. This work provides an alternative approach to develop conductive 3D MOFs as efficient electrocatalysts.

Enhanced cycloaddition between CO2 and epoxide over a bismuth-based metal organic framework due to a synergistic photocatalytic and photothermal effect.

The cycloaddition reaction between CO2 and epoxide is an efficient way to convert CO2 into high value-added chemicals. Therefore, it is particularly important to develop efficient catalysts that can catalyze the reaction under mild conditions. In this work, a metal-organic framework (Bi-HHTP, consisting of bismuth (Bi) as metal dots and 2,3,6,7,10,11-hexahydroxy-triphenylene (HHTP) as organic linkers) with zigzagging corrugated topology was successfully synthesized, which shows excellent catalytic activity under visible light irradiation. Various characterizations suggest that the excellent activity is derived from the following reasons: (1) the abundant exposed Bi sites provide Lewis sites for adsorption of epoxides and CO2; (2) the free holes produced over Bi-HHTP under light irradiation which could oxidize epoxide, which consequently facilitateing the subsequent ring-opening reaction; and (3) the existence of synergistic photocatalytic and photothermal effect in Bi-HHTP. This study provides a new avenue of developing bismuth-based metal organic frameworks to promote the efficiency of cycloaddition of CO2 under mild conditions.

Fabrication of Hematite Photoanode Consisting of (110)-Oriented Single Crystals.

In this work, α-Fe2 O3 photoanode consisted of (110)-oriented α-Fe2 O3 single crystals were synthesized by a facile hydrothermal method. By using particular additive (C4 MimBF4 ) and regulation of hydrothermal reaction time, the Fe-25 consisted of a single-layer of highly crystalline (110)-oriented crystals with fewer grain boundaries, which was vertically grown on the substrate. As a result, the charge separation efficiency and photoelectrochemical (PEC) performance of Fe-25A (Fe-25 after dehydration treatment) have been greatly improved. Fe-25A yields a photocurrent of 1.34 mA cm-2 (1.23 V vs RHE) and an incident photon-to-current conversion efficiency (IPCE) of 31.95 % (380 nm). With the assistance of cobalt-phosphate water oxidation catalyst (Co-Pi), the PEC performance could be further improved by enhancing the holes transfer at electrode/electrolyte interface and inhibiting surface recombination. Fe-25A/Co-Pi yields a photocurrent of 2.67 mA cm-2 (1.23 V vs RHE) and IPCE value of 50.8 % (380 nm), which is 3.67 times and 2.39 times as that of Fe-2A/Co-Pi. Our work provides a simple method to fabricate highly efficient Fe2 O3 photoanodes consist of characteristic (110)-oriented single crystals with high crystallinity and high quality interface contact to enhance charge separation efficiencies.

Characteristics and mechanisms of mosaicism in prenatal diagnosis cases by application of SNP array.

BACKGROUND: With the application of chromosome microarray, next-generation sequencing and other highly sensitive genetic techniques in disease diagnosis, the detection of mosaicism has become increasingly prevalent. This study involved a retrospective analysis of SNP array testing on 4512 prenatal diagnosis samples, wherein the characterization of mosaicism was explored and insights were gained into the underlying mechanisms thereof. RESULTS: Using SNP array, a total of 44 cases of mosaicism were identified among 4512 prenatal diagnostic cases; resulting in a detection rate of approximately 1.0%. The prevalence of mosaicism was 4.1% for chorionic villus sample, 0.4% for amniotic fluid, and 1.3% for umbilical cord blood. Of these cases, 29 were mosaic aneuploidy and 15 were mosaic segmental duplication/deletion. Three cases of mosaic trisomy 16 and three cases of mosaic trisomy 22 were diagnosed in the CVS samples, while four cases of mosaic trisomy 21 were detected in amniotic fluid and umbilical cord blood samples. The distribution pattern of mosaicism suggested trisomy rescue as the underlying mechanism. Structurally rearranged chromosomes were observed, including three cases with supernumerary marker chromosomes, three cases with dicentric chromosomes, and one case with a ring chromosome. All mosaic segmental duplication/deletion cases were the result of mitotic non-disjunction, with the exception of one case involving mosaic11q segmental duplication. CONCLUSION: Improved utilization of SNP arrays enables the characterization of mosaicism and facilitates the estimation of disease mechanisms and recurrence.

Boosting the Electrochemical 5-Hydroxymethylfurfural Oxidation by Balancing the Competitive Adsorption of Organic and OH- over Controllable Reconstructed Ni3 S2 /NiOx.

The electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) is a promising method for the efficient production of biomass-derived high-value-added chemicals. However, its practical application is limited by: 1) the low activity and selectivity caused by the competitive adsorption of HMF and OH- and 2) the low operational stability caused by the uncontrollable reconstruction of the catalyst. To overcome these limitations, a series of Ni3 S2 /NiOx -n catalysts with controllable compositions and well-defined structures are synthesized using a novel in situ controlled surface reconstruction strategy. The adsorption behavior of HMF and OH- can be continuously adjusted by varying the ratio of NiOx to Ni3 S2 on the catalysts surface, as indicated by in situ characterizations, contact angle analysis, and theoretical simulations. Owing to the balanced competitive adsorption of HMF and OH- , the optimized Ni3 S2 /NiOx -15 catalyst exhibited remarkable HMF electrocatalytic oxidation performance, with the current density reaching 366 mA cm-2 at 1.5 VRHE and the Faradaic efficiency of the product, 2,5-furanedicarboxylic acid, reaching 98%. Moreover, Ni3 S2 /NiOx -15 exhibits excellent durability, with its activity and structure remaining stable for over 100 h of operation. This study provides a new route for the design and construction of catalysts for value-added biomass conversion and offers new insights into enhancing catalytic performance by balancing competitive adsorption.

Coupling Benzylamine Oxidation with CO2 Photoconversion to Ethanol over a Black Phosphorus and Bismuth Tungstate S-Scheme Heterojunction.

Photoconversion of CO2 and H2 O into ethanol is an ideal strategy to achieve carbon neutrality. However, the production of ethanol with high activity and selectivity is challenging owing to the less efficient reduction half-reaction involving multi-step proton-coupled electron transfer (PCET), a slow C-C coupling process, and sluggish water oxidation half-reaction. Herein, a two-dimensional/two-dimensional (2D/2D) S-scheme heterojunction consisting of black phosphorus and Bi2 WO6 (BP/BWO) was constructed for photocatalytic CO2 reduction coupling with benzylamine (BA) oxidation. The as-prepared BP/BWO catalyst exhibits a superior photocatalytic performance toward CO2 reduction, with a yield of 61.3 µmol g-1 h-1 for ethanol (selectivity of 91 %).In situ spectroscopic studies and theoretical calculations reveal that S-scheme heterojunction can effectively promote photogenerated carrier separation via the Bi-O-P bridge to accelerate the PCET process. Meanwhile, electron-rich BP acts as the active site and plays a vital role in the process of C-C coupling. In addition, the substitution of BA oxidation for H2 O oxidation can further enhance the photocatalytic performance of CO2 reduction to C2 H5 OH. This work opens a new horizon for exploring novel heterogeneous photocatalysts in CO2 photoconversion to C2 H5 OH based on cooperative photoredox systems.

In Situ Formation of CoP/Co3 O4 Heterojunction for Efficient Overall Water Splitting.

Electrochemical water splitting is an environmentally friendly and effective energy storage method. However, it is still a huge challenge to prepare non-noble metal based electrocatalysts that possess high activity and long-term durability to realize efficient water splitting. Here, we present a novel method of low-temperature phosphating for preparing CoP/Co3 O4 heterojunction nanowires catalyst on titanium mesh (TM) substrate that can be used for oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and overall water splitting. CoP/Co3 O4 @TM heterojunction showed an excellent catalytic performance and long-term durability in 1.0 M KOH electrolyte. The overpotential of CoP/Co3 O4 @TM heterojunction was only 257 mV at 20 mA cm-2 during the OER process, and it could work stably more than 40 h at 1.52 V versus reversible hydrogen electrode (vs. RHE). During the HER process, the overpotential of CoP/Co3 O4 @TM heterojunction was only 98 mV at -10 mA cm-2 . More importantly, when used as anodic and cathodic electrocatalyst, they achieved 10 mA cm-2 at 1.59 V. The Faradaic efficiencies of OER and HER were 98.4 % and 99.4 %, respectively, outperforming Ru/Ir-based noble metal electrocatalysts and other non-noble metal electrocatalysts for overall water splitting.

Extended Light Absorption and Improved Charge Separation by Protonation of the Organic Ligand in a Bismuth-Based Metal-Organic Framework.

In this work, a new method to extend the light absorption and improve the photocatalytic activity of metal-organic frameworks (MOFs) with nitrogen-containing ligand is reported, namely, the protonation of nitrogen. Specifically, a protonated Bi-based MOF synthesized by a hydrothermal method (Bi-MMTAA-H, MMTAA=2-mercapto-4-methyl-5-thiazoleacetic acid) displays a wider visible light absorption than Bi-MMTAA-R with the same single-crystal structure, but synthesized by a reflux method. The redshifted light absorption was confirmed to be caused by the protonation of nitrogen in the thiazolyl ring in MMTAA. Moreover, this protonation also facilitates the charge separation and transfer and improves the photocatalytic activity of selective oxidation of α-terpinene to p-cymene. Our results provide a new idea for nitrogen-containing Bi-based MOFs to extend the light absorption and improve the photocatalytic performance.

Lead-Free Perovskite Cs2 SnBr6 /rGO Composite for Photocatalytic Selective Oxidation of 5-Hydroxymethylfurfural to 2,5-Diformylfuran.

Severe poisonousness and prolonged instability existing in organic-inorganic lead-based perovskite are two matters seriously hindering its potential future application in photocatalysis. Therefore, it is particularly important to explore ecology-friendly, air-stable and highly active metal-halide perovskites. Herein, a new and stable lead-free perovskite Cs2 SnBr6 decorated with reduced graphene oxide (rGO), is synthesized and employed in the photocatalytic organic conversion. The as-prepared Cs2 SnBr6 is ultrastable, exhibiting no clear changes after being placed in the air for six months. The Cs2 SnBr6 /rGO composite shows excellent photocatalytic activity in photo-driven-oxidation of 5-hydroxymethylfurfural (HMF) to high value enclosed 2,5-diformylfuran (DFF), achieving>99.5 % conversion of HMF and 88 % DFF selectivity in the presence of green oxidant O2 . Comprehensive characterizations disclose a multistep reaction mechanism, demonstrating that the molecular oxygen, photogenerated carriers, ⋅O2 - and 1 O2 altogether synergistically participate in the effective photo-driven conversion of HMF to DFF. This work expands the material gallery towards selective organic conversion and environmentally friendly perovskite options for photocatalytic application.

Integrating Mixed Halide Perovskite Photocatalytic HI Splitting and Electrocatalysis into a Loop for Efficient and Robust Pure Water Splitting.

Developing a hydrogen economy to replace traditional fossil fuels is essential for sustainable human development. As two promising H2 production strategies, photocatalytic and electrocatalytic water splitting with large reaction energy barriers still face the great challenges of poor solar-to-hydrogen efficiency and large electrochemical overpotentials, respectively. Herein, a new strategy is proposed to disassemble the difficult pure water splitting into two parts that are easy to implement, namely mixed halide perovskite photocatalytic HI splitting for H2 production, and simultaneous electrocatalytic I3 - reduction and O2 production. The efficient charge separation, abundant H2 production active sites, and a small HI splitting energy barrier contribute to the superior photocatalytic H2 production activity of MoSe2 /MAPbBr3- x Ix (CH3 NH3 +  = MA). Subsequent electrocatalytic I3 - reduction and O2 production reactions only need a small voltage of 0.92 V to drive, which is far lower than that of the electrocatalytic pure water splitting (>1.23 V). The molar ratio of H2 (6.99 mmol g-1 ) to O2 (3.09 mmol g-1 ) produced during the first photocatalytic and electrocatalytic cycle is close to 2:1, and the continuous circulation of I3 - /I- between the photocatalytic and electrocatalytic systems can achieve efficient and robust pure water splitting.