Integration of photothermal water evaporation with photocatalytic microplastics upcycling via nanofluidic thermal management.

Photothermal heating and photocatalytic treatment are two solar-driven water processing approaches by harnessing NIR and UV-vis light, respectively, which can fully utilize solar energy if integrated. However, it remains a challenge to achieve high performance in both approaches when integrated in a material due to uncontrollable heat diffusion. Here, we report a demonstration of heat confinement on photothermal sites and fluid cooling on photocatalysis sites at the nanoscale, within a well-designed heat and fluid confinement nanofiber reactor. Photothermal and photocatalytic nanostructures were alternatively aligned in electrospun nanofibers for on-demand nanofluidic thermal management as well as easy folding into 3D structures with enhanced light utilization and mass transfer. Such a design showed simultaneously high photothermal evaporation rate (2.59 kg m-2 h-1, exceeding the limit rate) and efficient photocatalytic upcycling of microplastics pollutant into valued products. Enabled by controlled photothermal heating, the valued main product (i.e., methyl acetate) can be evaporated out with 100% selectivity by in situ separation.

Highly Efficient and Selective Light-Driven Dry Reforming of Methane by a Carbon Exchange Mechanism.

Dry reforming of methane (DRM) is a promising technique for converting greenhouse gases (namely, CH4 and CO2) into syngas. However, traditional thermocatalytic processes require high temperatures and suffer from low selectivity and coke-induced instability. Here, we report high-entropy alloys loaded on SrTiO3 as highly efficient and coke-resistant catalysts for light-driven DRM without a secondary source of heating. This process involves carbon exchange between reactants (i.e., CO2 and CH4) and oxygen exchange between CO2 and the lattice oxygen of supports, during which CO and H2 are gradually produced and released. Such a mechanism deeply suppresses the undesired side reactions such as reverse water-gas shift reaction and methane deep dissociation. Impressively, the optimized CoNiRuRhPd/SrTiO3 catalyst achieves ultrahigh activity (15.6/16.0 mol gmetal-1 h-1 for H2/CO production), long-term stability (∼150 h), and remarkable selectivity (∼0.96). This work opens a new avenue for future energy-efficient industrial applications.

Highly Efficient Iron-Based Catalyst for Light-Driven Selective Hydrogenation of Nitroarenes.

Light-driven hydrogenation of nitro compounds to functionalized amines is of great importance yet a challenge for practical applications, which calls for the development of high-performance, nonprecious photocatalysts and efficient catalytic systems. Herein, we report a high-efficiency Fe3O4@TiO2 photocatalyst via a sol-gel and subsequent pyrolysis strategy, which exhibits desirable photothermal hydrogenation performance of nitro compounds to functionalized amines with the excellent selectivity of >90% exceeding those of the state-of-the-art heterogeneous photocatalysts. Our experimental results and theoretical calculations for the first time reveal that Fe3O4 is the major active phase, and the strong metal-support interaction between Fe3O4 and reducible TiO2 further leads to performance improvement, taking advantage of the enhanced photothermal effect and the improved adsorption for the reactant and hydrazine hydrate. Notably, a variety of halonitrobenzenes and pharmaceutical intermediates can be completely converted to functionalized amines with high selectivities, even in gram-scale reactions. This work provides a new insight into the rational design of nonprecious photo/thermo-catalysts for other catalytic reactions.

Continuous Flow System for Highly Efficient and Durable Photocatalytic Oxidative Coupling of Methane.

Photocatalytic oxidative coupling of methane (OCM) into value-added industrial chemicals offers an appealing green technique for achieving sustainable development, whereas it encounters double bottlenecks in relatively low methane conversion rate and severe overoxidation. Herein, we engineer a continuous gas flow system to achieve efficient photocatalytic OCM while suppressing overoxidation by synergizing the moderate active oxygen species, surface plasmon-mediated polarization, and multipoint gas intake flow reactor. Particularly, a remarkable CH4 conversion rate of 218.2 µmol h-1 with an excellent selectivity of ∼90% toward C2+ hydrocarbons and a remarkable stability over 240 h is achieved over a designed Au/TiO2 photocatalyst in our continuous gas flow system with a homemade three-dimensional (3D) printed flow reactor. This work provides an informative concept to engineer a high-performance flow system for photocatalytic OCM by synergizing the design of the reactor and photocatalyst to synchronously regulate the mass transfer, activation of reactants, and inhibition of overoxidation.

Tunable Impedance of Cobalt Loaded Carbon for Wide-Range Electromagnetic Wave Absorption.

Impedance matching modulation of the electromagnetic wave (EMW) absorbers toward broad effective absorption bandwidth (EAB) is the ultimate aim in EMW attenuation applications. Here, a Joule heating strategy is reported for preparation of the Co-loaded carbon (Co/C) absorber with tunable impedance characteristics. Typically, the size of the Co can be regulated to range from single-atoms to clusters, and to nanocrystals. The varied sizes of the Co combined with different graphitization degrees of carbon can result in different relative input impedances and electromagnetic loss, leading to the tunable EMW absorption properties of the Co/C absorber. By meticulously coalescing the different prepared Co/C, the working frequency can be easily tuned, covering Ku, X, and C bands. Furthermore, the Co/C demonstrates a high EMW attenuation due to its unique dielectric loss capability and magnetic loss characteristics. The abundant interfaces of Co/C can also contribute to the enhanced interfacial polarization for improving EMW attenuation. This work demonstrates the importance of optimizing the metal and carbon interaction to the impedance matching toward wide EAB of the EMW absorbers.

Tm,Ho:YLF waveguide lasers at 2.05†µm.

In this work, we report on the first, to our knowledge, 2.05-µm laser based on femtosecond-laser direct written (FsLDW) Tm,Ho:YLF cladding waveguides. A channel waveguide with a 90-µm diameter "fiber-like" low-index cladding is fabricated in a 6 at. % Tm3+, 0.4 at. % Ho3+:LiYF4 crystal by FsLDW. Pumped by Ti:sapphire laser at 795.1 nm, the fabricated waveguide supports efficient lasing oscillation at 2050 nm with a maximum output power of 47.5 mW, a minimum lasing threshold of 181 mW, and a slope efficiency of 20.1%. The impacts of cavity conditions and polarizations of the pump light on the obtained lasing performance are well studied. The experimental results obtained in this study demonstrate the great potential of utilizing Tm,Ho:YLF and FsLDW for the development of durable mid-infrared lasers featuring compact designs.

Bridging molecular photosensitizer and catalyst on carbon nanotubes toward enhanced selectivity and durability for CO2 photoreduction.

Homogenous molecular photocatalysts for CO2 reduction, especially metal complex-based photosensitizer‒catalyst assemblages, have been attracting extensive research interests due to their efficiency and customizability. However, their low durability and recyclability limit practical applications. In this work, we immobilized the catalysts of metal terpyridyl complexes and the photosensitizer of [Ru(bpy)3]Cl2 onto the surface of carbon nanotubes through covalent bonds and electrostatic interactions, respectively, transforming the homogeneous system into a heterogeneous one. Our characterizations prove that these metal complexes are well dispersed on CNTs with a high loading (ca. 12 wt.%). Photocatalytic measurements reveal that catalytic activity is remarkably enhanced when the molecular catalysts are anchored, which is three times higher than that of homogeneous molecular catalysts. Moreover, when the photosensitizer of [Ru(bpy)3]Cl2 is immobilized, the side reaction of hydrogen evolution is completely suppressed and the selectivity for CO production reaches 100%, with its durability also significantly improved. This work provides an effective pathway for constructing heterogeneous photocatalysts based on rational assembly of efficient molecular photosensitizers and catalysts.

Biomimetic Phthalocyanine-Based Covalent Organic Frameworks with Tunable Pendant Groups for Electrocatalytic CO2 Reduction.

Electrocatalytic carbon dioxide reduction reaction (CO2RR) is an effective way of converting CO2 into value-added products using renewable energy, whose activity and selectivity can be in principle maneuvered by tuning the microenvironment near catalytic sites. Here, we demonstrate a strategy for tuning the microenvironment of CO2RR by learning from the natural chlorophyll and heme. Specifically, the conductive covalent organic frameworks (COFs) linked by piperazine serve as versatile supports for single-atom catalysts (SACs), and the pendant groups modified on the COFs can be readily tailored to offer different push-pull electronic effects for tunable microenvironment. As a result, while all the COFs exhibit high chemical structure stability under harsh conditions and good conductivity, the addition of -CH2NH2 can greatly enhance the activity and selectivity of CO2RR. As proven by experimental characterization and theoretical simulation, the electron-donating group (-CH2NH2) not only reduces the surface work function of COF, but also improves the adsorption energy of the key intermediate *COOH, compared with the COFs with electron-withdrawing groups (-CN, -COOH) near the active sites. This work provides insights into the microenvironment modulation of CO2RR electrocatalysts at the molecular level.

Tailoring Second Coordination Sphere for Tunable Solid-Liquid Interfacial Charge Transfer toward Enhanced Photoelectrochemical H2 Production.

The recombination of photogenerated charge carriers severely limits the performance of photoelectrochemical (PEC) H2 production. Here, we demonstrate that this limitation can be overcome by optimizing the charge transfer dynamics at the solid-liquid interface via molecular catalyst design. Specifically, the surface of a p-Si photocathode is modulated using molecular catalysts with different metal atoms and organic ligands to improve H2 production performance. Co(pda-SO3H)2 is identified as an efficient and durable catalyst for H2 production through the rational design of metal centers and first/second coordination spheres. The modulation with Co(pda-SO3H)2, which contains an electron-withdrawing -SO3H group in the second coordination sphere, elevates the flat-band potential of the polished p-Si photocathode and nanoporous p-Si photocathode by 81 mV and 124 mV, respectively, leading to the maximized energy band bending and the minimized interfacial carrier transport resistance. Consequently, both the two photocathodes achieve the Faradaic efficiency of more than 95 % for H2 production, which is well maintained during 18 h and 21 h reaction, respectively. This work highlights that the band-edge engineering by molecular catalysts could be an important design consideration for semiconductor-catalyst hybrids toward PEC H2 production.

Abiotic Methane Production Driven by Ubiquitous Non-Fenton-Type Reactive Oxygen Species.

Abiotic CH4 production driven by Fenton-type reactive oxygen species (ROS) has been confirmed to be an indispensable component of the atmospheric CH4 budget. While the chemical reactions independent of Fenton chemistry to ROS are ubiquitous in nature, it remains unknown whether the produced ROS can drive abiotic CH4 production. Here, we first demonstrated the abiotic CH4 production at the soil-water interface under illumination. Leveraging this finding, polymeric carbon nitrides (CNx) as a typical analogue of natural geobattery material and dimethyl sulfoxide (DMSO) as a natural methyl donor were used to unravel the underlying mechanisms. We revealed that the ROS, photocatalytically produced by CNx, can oxidize DMSO into CH4 with a high selectivity of 91.5 %. Such an abiotic CH4 production process was further expanded to various non-Fenton-type reaction systems, such as electrocatalysis, pyrocatalysis and sonocatalysis. This work provides insights into the geochemical cycle of abiotic CH4, and offers a new route to CH4 production via integrated energy development.

Highly Stable Perovskite Oxides for Electrocatalytic Acidic NOx - Reduction Streamlining Ammonia Synthesis from Air.

Electrochemical nitrogen oxide ions reduction reaction (NOx -RR) shows great opportunity for ammonia production under ambient conditions. Yet, performing NOx -RR in strong acidic conditions remains challenging due to the corrosion effect on the catalyst and competing hydrogen evolution reactions. Here, we demonstrate a stable La1.5Sr0.5Ni0.5Fe0.5O4 perovskite oxide for the NOx -RR at pH 0, achieving a Faradaic efficiency for ammonia of approaching 100 % at a current density of 2 A cm-2 in a H-type cell. At industrially relevant current density, the NOx -RR system shows stable cell voltage and Faradaic efficiency for >350 h in membrane electrode assembly (MEA) at pH 0. By integrating the catalyst in a stacked MEA with a series connection, we have successfully obtained a record-breaking 2.578 g h-1 NH3 production rate at 20 A. This catalyst's unique acid-operability streamlines downstream ammonia utilization for direct ammonium salt production and upstream integration with NOx sources. Techno-economic and lifecycle assessments reveal substantial economic advantages for this ammonia production strategy, even when coupled with a plasma-based NOx production system, presenting a sustainable complement to the conventional Haber-Bosch process.

Construction of Frustrated Lewis Pairs in Poly(heptazine Imide) Nanosheets via Hydrogen Bonds for Boosting CO2 Photoreduction.

The creation of frustrated Lewis pairs on catalyst surface is an effective strategy for tuning CO2 activation. The critical step in the formation of frustrated Lewis pairs is the spatial effect of proximal Lewis acid-Lewis base pairs. Here, we demonstrate a facile surface functionalization methodology that enables hydrogen bonding between N and H atoms to mediate the construction of frustrated Lewis pairs in poly(heptazine imide), thereby increasing the propensity to activate CO2 molecules. Experimental and theoretical results show that the construction of active hydrogen bonding regions can facilitate the bending of CO2 molecules. Furthermore, the delocalization of electron clouds induced by the hydrogen bonding-mediated frustrated Lewis pairs can promote the heterolytic cleavage and photocatalytic conversion of CO2. This work highlights the potential of utilizing hydrogen bonding-mediated strategy in heterogeneously photocatalytic activation of CO2 over polymer materials.

Concentrated Formic Acid from CO2 Electrolysis for Directly Driving Fuel Cell.

The production of formic acid via electrochemical CO2 reduction may serve as a key link for the carbon cycle in the formic acid economy, yet its practical feasibility is largely limited by the quantity and concentration of the product. Here we demonstrate continuous electrochemical CO2 reduction for formic acid production at 2 M at an industrial-level current densities (i.e., 200 mA cm-2 ) for 300 h on membrane electrode assembly using scalable lattice-distorted bismuth catalysts. The optimized catalysts also enable a Faradaic efficiency for formate of 94.2 % and a highest partial formate current density of 1.16 A cm-2 , reaching a production rate of 21.7 mmol cm-2 h-1 . To assess the practicality of this system, we perform a comprehensive techno-economic analysis and life cycle assessment, showing that our approach can potentially substitute conventional methyl formate hydrolysis for industrial formic acid production. Furthermore, the resultant formic acid serves as direct fuel for air-breathing formic acid fuel cells, boasting a power density of 55 mW cm-2 and an exceptional thermal efficiency of 20.1 %.

Electrosynthesis of an Improbable Directly Bonded Phosphorene-Fullerene Heterodimensional Hybrid toward Boosted Photocatalytic Hydrogen Evolution.

Phosphorene and fullerene are representative two-dimensional (2D) and zero-dimensional (0D) nanomaterials respectively, constructing their heterodimensional hybrid not only complements their physiochemical properties but also extends their applications via synergistic interactions. This is however challenging because of their diversities in dimension and chemical reactivity, and theoretical studies predicted that it is improbable to directly bond C60 onto the surface of phosphorene due to their strong repulsion. Here, we develop a facile electrosynthesis method to synthesize the first phosphorene-fullerene hybrid featuring fullerene surface bonding via P-C bonds. Few-layer black phosphorus nanosheets (BPNSs) obtained from electrochemical exfoliation react with C60 2- dianion prepared by electroreduction of C60, fulfilling formation of the "improbable" phosphorene-fullerene hybrid (BPNS-s-C60). Theoretical results reveal that the energy barrier for formation of [BPNS-s-C60]2- intermediate is significantly decreased by 1.88 eV, followed by an oxidization reaction to generate neutral BPNS-s-C60 hybrid. Surface bonding of C60 molecules not only improves significantly the ambient stability of BPNSs, but also boosts dramatically the visible light and near-infrared (NIR) photocatalytic hydrogen evolution rates, reaching 1466 and 1039 µmol h-1 g-1 respectively, which are both the highest values among all reported BP-based metal-free photocatalysts.

Tandem Synergistic Effect of Cu-In Dual Sites Confined on the Edge of Monolayer CuInP2 S6 toward Selective Photoreduction of CO2 into Multi-Carbon Solar Fuels.

One-unit-cell, single-crystal, hexagonal CuInP2 S6 atomically thin sheets of≈0.81 nm in thickness was successfully synthesized for photocatalytic reduction of CO2 . Exciting ethene (C2 H4 ) as the main product was dominantly generated with the yield-based selectivity reaching ≈56.4 %, and the electron-based selectivity as high as ≈74.6 %. The tandem synergistic effect of charge-enriched Cu-In dual sites confined on the lateral edge of the CuInP2 S6 monolayer (ML) is mainly responsible for efficient conversion and high selectivity of the C2 H4 product as the basal surface site of the ML, exposing S atoms, can not derive the CO2 photoreduction due to the high energy barrier for the proton-coupled electron transfer of CO2 into *COOH. The marginal In site of the ML preeminently targets CO2 conversion to *CO under light illumination, and the *CO then migrates to the neighbor Cu sites for the subsequent C-C coupling reaction into C2 H4 with thermodynamic and kinetic feasibility. Moreover, ultrathin structure of the ML also allows to shorten the transfer distance of charge carriers from the interior onto the surface, thus inhibiting electron-hole recombination and enabling more electrons to survive and accumulate on the exposed active sites for CO2 reduction.

Engineering surface lattice hydroxyl groups toward highly efficient photocatalytic methane coupling.

Nb3O7(OH) containing abundant surface lattice hydroxyl groups, combining with loaded Au nanoparticles as the cocatalyst, was employed as a photocatalyst enabling highly efficient photocatalytic CH4 coupling to C2H6 under mild conditions. In situ spectroscopy technique revealed that the surface lattice hydroxyl groups play a vital role in promoting the activation of CH4 to produce the methoxy intermediates, contributing to significantly enhanced catalytic performance for CH4 conversion.

Recent advances of metal active sites in photocatalytic CO2 reduction.

Photocatalytic CO2 reduction captures solar energy to convert CO2 into hydrocarbon fuels, thus shifting the dependence on rapidly depleting fossil fuels. Among the various proposed photocatalysts, systems containing metal active sites (MASs) possess obvious advantages, such as effective photogenerated carrier separation, suitable adsorption and activation of intermediates, and achievable C-C coupling to generate multi-carbon (C2+) products. The present review aims to summarize the typical photocatalytic materials with MAS, highlighting the critical role of different formulations of MAS in CO2 photoreduction, especially for C2+ product generation. State-of-the-art progress in the characterization and theoretical calculations for MAS-containing photocatalysts is also emphasized. Finally, the challenges and prospects of catalytic systems involving MAS for solar-driven CO2 conversion are outlined, providing inspiration for the future design of materials for efficient photocatalytic energy conversion.

Recent progress of heterogeneous catalysts for transfer hydrogenation under the background of carbon neutrality.

Under the background of carbon neutrality, the direct conversion of greenhouse CO2 to high value added fuels and chemicals is becoming an important and promising technology. Among them, the generation of liquid C1 products (formic acid and methanol) has made great progress; nevertheless, it encounters the problem of how to use it efficiently to solve the overcapacity issue. In this review, we suggest that the catalytic transfer hydrogenation using formic acid and methanol as the hydrogen sources is a critical and potential route for the substitution for the fossil fuel-derived H2 to generate essential bulk and fine chemicals. We mainly focus on summarizing the recent progress of heterogeneous catalysts in such reactions, including thermal- and photo-catalytic processes. Finally, we also propose some challenges and opportunities for this development.

Sustainable all-weather CO2 utilization by mimicking natural photosynthesis in a single material.

Solar-driven CO2 conversion into hydrocarbon fuels is a sustainable approach to synchronously alleviating the energy crisis and achieving net CO2 emissions. However, the dependence of the conversion process on solar illumination hinders its practical application due to the intermittent availability of sunlight at night and on cloudy or rainy days. Here, we report a model material of Pt-loaded hexagonal tungsten trioxide (Pt/h-WO3) for decoupling light and dark reaction processes, demonstrating the sustainable CO2 conversion under dark conditions for the first time. In such a material system, hydrogen atoms can be produced by photocatalytic water splitting under solar illumination, stored together with electrons in the h-WO3 through the transition of W6+ to W5+ and spontaneously released to trigger catalytic CO2 reduction under dark conditions. Furthermore, we demonstrate using natural light that CH4 production can persist at night and on rainy days, proving the accomplishment of all-weather CO2 conversion via a sustainable way.

Full-Space Electric Field in Mo-Decorated Zn2In2S5 Polarization Photocatalyst for Oriented Charge Flow and Efficient Hydrogen Production.

Integration of photocatalytic hydrogen (H2) evolution with oxidative organic synthesis presents a highly attractive strategy for the simultaneous production of clean H2 fuel and high-value chemicals. However, the sluggish dynamics of photogenerated charge carriers across the photocatalysts result in low photoconversion efficiency, hindering the wide applications of such a technology. Herein, this work overcomes this limitation by inducing the full-space electric field via charge polarization engineering on a Mo cluster-decorated Zn2In2S5 (Mo-Zn2In2S5) photocatalyst. Specifically, this full-space electric field arises from a cascade of the bulk electric field (BEF) and local surface electric field (LSEF), triggering the oriented migration of photogenerated electrons from [Zn-S] regions to [In-S] regions and eventually to Mo cluster sites, ensuring efficient separation of bulk and surface charge carriers. Moreover, the surface Mo clusters induce a tip enhancement effect to optimize charge transfer behavior by augmenting electrons and proton concentration around the active sites on the basal plane of Zn2In2S5. Notably, the optimized Mo1.5-Zn2In2S5 catalyst achieves exceptional H2 and benzaldehyde production rates of 34.35 and 45.31 mmol gcat -1 h-1, respectively, outperforming pristine ZnIn2S4 by 3.83- and 4.15-fold. These findings mark a significant stride in steering charge flow for enhanced photocatalytic performance.