Direct Electroreduction of Low-Concentration CO: Progress and Perspective.

The conversion of CO into carbon-based fuels and chemicals via the electrocatalytic CO reduction reaction (CORR) offers an attractive route to reducing the CO emission for carbon neutrality. Currently, high-purity CO gas has been widely used as the feedstock for most of the CORR studies, while CO sources with a typically low concentration impose the extra cost for CO capture and purification steps. The direct utilization of low-concentration CO for the CORR is a promising approach to substantially address this problem.

Hydrogen-bonded organic frameworks for photocatalytic synthesis of hydrogen peroxide.

Photocatalysis provides a sustainable and environment-friendly strategy to produce HO, yet the catalytic efficiency of HO overall photosynthesis (O + 2HO → 2HO) needs to be further improved, especially in the absence of additional cocatalysts, photosensitizers and sacrificial agents. Here we find that hydrogen-bonded organic frameworks can serve as photocatalysts for HO overall photosynthesis under the above-mentioned conditions. Specifically, we constructed a donor-acceptor hydrogen-bonded organic framework that exhibits a high photocatalytic activity for HO overall photosynthesis, with a production rate of 681.

Tailoring Lewis Acidity of Metal Oxides on Nickel to Boost Electrocatalytic Hydrogen Evolution in Neutral Electrolyte.

Neutral-pH water splitting for hydrogen production features a benign environment that could alleviate catalyst and electrolyzer corrosion but calls for the corresponding high-efficiency and earth-abundant hydrogen evolution reaction (HER) catalysts. Herein, we first designed a series of metal oxides decorated on Ni as the model catalysts and found a volcano-shaped relationship between the Lewis acidity of Ni/metal oxides and HER activity in neutral media. The Ni/ZnO with the optimum Lewis acidity could balance water dissociation and hydroxyl desorption, thereby greatly boosting the HER.

Identifying the Key Photosensitizing Factors over Metal-Organic Frameworks for Selective Control of O and O⋅ Generation.

The reaction pathway, product selectivity and catalytic efficiency of photo-oxidation are highly dependent on the specific reactive oxygen species (ROS), such as singlet oxygen (O) and superoxide (O⋅), generated via the sensitization of O by photosensitizers. Studies on uncovering the role of photosensitizing factors on the selective control of O and O⋅ generation are significant but remain underexplored. Here, we constructed a photosensitizing metal-organic framework molecular platform (UiO-1-UiO-4) by elaborately engineering Ir(III) complex ligands with pyrenyl group for modulating photosensitizing factors and elucidating their impact on ROS generation.

Direct Partial Transformation of 2D Antimony Oxybromide to Halide Perovskite Heterostructure for Efficient CO Photoreduction.

The photocatalytic activity of lead-free perovskite heterostructures currently suffers from low efficiency due to the lack of active sites and the inadequate photogenerated carrier separation, the latter of which is hindered by slow charge transfer at the heterostructure interfaces. Herein, a facile strategy is reported for the construction of lead-free halide-perovskite-based heterostructure with swift interfacial charge transfer, achieved through direct partial conversion of 2D antimony oxybromide SbOBr to generate CsSbBr/SbOBr heterostructure. Compared to the traditional electrostatic self-assembly method, this approach endows the CsSbBr/SbOBr heterostructure with a tightly interconnected interface through in situ partial conversion, significantly accelerating interfacial charge transfer and thereby enhancing the separation efficiency of photogenerated carriers.

Porous Supramolecular Crystalline Materials for Photocatalysis.

Porous supramolecular crystalline materials (PSCMs), such as hydrogen-bonded organic frameworks (HOFs), π frameworks, can be defined as a type of porous supramolecular assemblies stabilized by hydrogen-bonding, π-π stacking and other non-covalent interactions. Benefiting from the unique features of mild synthesis conditions, well-defined and synthetically tailorable structures, easy healing and regeneration, PSCMs have garnered widespread interest in research fields including molecular recognition, sensor, gas storage and separation. Moreover, they have emerged as promising photocatalysts because these PSCMs could be readily endowed with optical function, and the hydrogen-bonding and π-π stacking can offer channels for electron transfer to boost the photocatalytic activity.

In Situ Growth of Metal-Organic Layer on Polyoxometalate-etching CuO to Boost CO Reduction with High Stability.

Low-cost CuO with a suitable band gap holds great potential for solar utilization. However severe photocorrosion and weak CO capture capability have significantly hindered their application in artificial photosynthesis. Herein, polyoxometalate (POM)-etching and in situ growth of metal-organic framework (MOF) can simultaneously incorporate electron-sponge and HKUST protective layer into CuO.

Boosting the durability of RuO via confinement effect for proton exchange membrane water electrolyzer.

Ruthenium dioxide has attracted extensive attention as a promising catalyst for oxygen evolution reaction in acid. However, the over-oxidation of RuO into soluble HRuO species results in a poor durability, which hinders the practical application of RuO in proton exchange membrane water electrolysis. Here, we report a confinement strategy by enriching a high local concentration of in-situ formed HRuO species, which can effectively suppress the RuO degradation by shifting the redox equilibrium away from the RuO over-oxidation, greatly boosting its durability during acidic oxygen evolution.

Polyoxometalate Confined Synthesis of BiVO Nanocluster for Urea Production with Remarkable O/N Tolerance.

Urea electrosynthesis from flue gas and NO under operating conditions represents a promising alternative technology to traditional energy-intensive industrial process. Herein, we explore a polyoxometalate confined synthesis strategy to prepare ultrafine BiVO nanocluster by pre-incorporating [VO] into NH-MIL-101-Al (MIL) framework. The resulting BiVO@MIL-n can efficiently drive co-reduction of NO and CO to urea.

Constructing S-scheme heterojunction CsBiBr/BiOBr via in-situ partial conversion to boost photocatalytic N fixation.

The judicious construction of interfaces with swift charge communication to enhance the utilization efficiency of photogenerated carriers is a viable strategy for boosting the photocatalytic performance of heterojunctions. Herein, an in-situ partial conversion strategy is reported for decorating lead-free halide perovskite CsBiBr nanocrystals onto BiOBr hollow nanotube, resulting in the formation of an S-scheme heterojunction CsBiBr/BiOBr. This unique in-situ growth approach imparts a closely contacted interface to the CsBiBr/BiOBr heterojunction, facilitating interfacial electron transfer and spatial charge separation compared to a counterpart (CsBiBr:BiOBr) fabricated via traditional electrostatic self-assembly.

Polyoxometalate-Based Single-Atom Catalyst with Precise Structure and Extremely Exposed Active Site for Efficient H Evolution.

Single-atom catalysts with precise structure and extremely high catalytic efficiency remain a fervent focus in the fields of materials chemistry and catalytic science. Herein, a nickel-substituted polyoxometalate (POM) {NiSbO(HO)[β-Ni(hmta)SbWO]} (NiPOM) with one extremely exposed nickel site [NiO(HO)] was synthesized using the conventional aqueous method. The uniform dispersion of single nickel center with well-defined structure was facilely achieved by anchoring nanosized NiPOM on graphene oxide (GO).

A Supramolecular-Nanocage-Based Framework Stabilized by π-π Stacking Interactions with Enhanced Photocatalysis.

π frameworks, defined as a type of porous supramolecular materials weaved from conjugated molecular units by π-π stacking interactions, provide a new direction in photocatalysis. However, such examples are rarely reported. Herein, we report a supramolecular-nanocage-based π framework constructed from a photoactive Cu(I) complex unit.

Oxyanion Engineering on RuO for Efficient Proton Exchange Membrane Water Electrolysis.

In acidic proton exchange membrane water electrolysis (PEMWE), the anode oxygen evolution reaction (OER) catalysts rely heavily on the expensive and scarce iridium-based materials. Ruthenium dioxide (RuO) with lower price and higher OER activity, has been explored for the similar task, but has been restricted by the poor stability. Herein, we developed an anion modification strategy to improve the OER performance of RuO in acidic media.

Modulating the Microenvironments of Robust Metal Hydrogen-Bonded Organic Frameworks for Boosting Photocatalytic Hydrogen Evolution.

Hydrogen-bonded organic frameworks (HOFs) are outstanding candidates for photocatalytic hydrogen evolution. However, most of reported HOFs suffer from poor stability and photocatalytic activity in the absence of Pt cocatalyst. Herein, a series of metal HOFs (Co-HOF-X, X=COOMe, Br, tBu and OMe) have been rationally constructed based on dinuclear cobalt complexes, which exhibit exceptional stability in the presence of strong acid (12 M HCl) and strong base (5 M NaOH) for at least 10 days.

Covalent Bonding of Salen Metal Complexes with Pyrene Chromophores to Porous Polymers for Photocatalytic Hydrogen Evolution.

The development of low-cost and efficient photocatalysts to achieve water splitting to hydrogen (H) is highly desirable but remains challenging. Herein, we design and synthesize two porous polymers (Co-Salen-P and Fe-Salen-P) by covalent bonding of salen metal complexes and pyrene chromophores for photocatalytic H evolution. The catalytic results demonstrate that the two polymers exhibit excellent catalytic performance for H generation in the absence of additional noble-metal photosensitizers and cocatalysts.

Single Dispersion of Fe(HO)-Based Polyoxometalate on Polymeric Carbon Nitride for Biomimetic CH Photooxidation.

Direct methane conversion to value-added oxygenates under mild conditions with in-depth mechanism investigation has attracted wide interest. Inspired by methane monooxygenase, the KNaFe(HO){[γ-SiWOFe(HO)]}·25HO polyoxometalate (Fe-POM) with well-defined Fe(HO) sites is synthesized to clarify the key role of Fe species and their microenvironment toward CH photooxidation. The Fe-POM can efficiently drive the conversion of CH to HCOOH with a yield of 1570.

Earth-abundant Zn-dipyrrin chromophores for efficient CO photoreduction.

The development of strong sensitizing and Earth-abundant antenna molecules is highly desirable for CO reduction through artificial photosynthesis. Herein, a library of Zn-dipyrrin complexes (-) are rationally designed via precisely controlling their molecular configuration to optimize strong sensitizing Earth-abundant photosensitizers. Upon visible-light excitation, their special geometry enables intramolecular charge transfer to induce a charge-transfer state, which was first demonstrated to accept electrons from electron donors.

Single-cluster Functionalized TiO Nanotube Array for Boosting Water Oxidation and CO Photoreduction to CHOH.

Solar-driven CO reduction and water oxidation to liquid fuels represents a promising solution to alleviate energy crisis and climate issue, but it remains a great challenge for generating CHOH and CHCHOH dominated by multi-electron transfer. Single-cluster catalysts with super electron acceptance, accurate molecular structure, customizable electronic structure and multiple adsorption sites, have led to greater potential in catalyzing various challenging reactions. However, accurately controlling the number and arrangement of clusters on functional supports still faces great challenge.

Building Co-N-Based UiO-MOF to Expand Design Parameters for MOF Photosensitization.

The construction of secondary building units (SBUs) in versatile metal-organic frameworks (MOFs) represents a promising method for developing multi-functional materials, especially for improving their sensitizing ability. Herein, we developed a dual small molecules auxiliary strategy to construct a high-nuclear transition-metal-based UiO-architecture Co-MOF-BDC with visible-light-absorbing capacity. Remarkably, the N molecule in hexadecameric cobalt azide SBU offers novel modification sites to precise bonding of strong visible-light-absorbing chromophores via click reaction.