Explore the vast range of titles available.

Recently developed solid-state catalysts can mediate carbon dioxide (CO 2 ) electroreduction to valuable products at high rates and selectivities. However, under commercially relevant current densities of > 200 milliamperes per square centimeter (mA cm −2 ), catalysts often undergo particle agglomeration, active-phase change, and/or element dissolution, making the long-term operational stability a considerable challenge. Here we report an indium sulfide catalyst that is stabilized by adding zinc in the structure and shows dramatically improved stability. The obtained ZnIn 2 S 4 catalyst can reduce CO 2 to formate with 99.3% Faradaic efficiency at 300 mA cm −2 over 60 h of continuous operation without decay. By contrast, similarly synthesized indium sulfide without zinc participation deteriorates quickly under the same conditions. Combining experimental and theoretical studies, we unveil that the introduction of zinc largely enhances the covalency of In-S bonds, which “locks” sulfur—a catalytic site that can activate H 2 O to react with CO 2 , yielding HCOO* intermediates—from being dissolved during high-rate electrolysis. Developing durable catalysts for carbon dioxide reduction to formate at commercial-scale current densities is challenging. This work reports that indium sulfide stabilized through zinc incorporation can produce formate efficiently and quickly at high current densities over long timescales.

Although much effort has been devoted to improving photoelectrochemical water splitting of hematite (α-Fe 2 O 3 ) due to its high theoretical solar-to-hydrogen conversion efficiency of 15.5%, the low applied bias photon-to-current efficiency remains a huge challenge for practical applications. Herein, we introduce single platinum atom sites coordination with oxygen atom (Pt-O/Pt-O-Fe) sites into single crystalline α-Fe 2 O 3 nanoflakes photoanodes (SAs Pt:Fe 2 O 3 -Ov). The single-atom Pt doping of α-Fe 2 O 3 can induce few electron trapping sites, enhance carrier separation capability, and boost charge transfer lifetime in the bulk structure as well as improve charge carrier injection efficiency at the semiconductor/electrolyte interface. Further introduction of surface oxygen vacancies can suppress charge carrier recombination and promote surface reaction kinetics, especially at low potential. Accordingly, the optimum SAs Pt:Fe 2 O 3 -Ov photoanode exhibits the photoelectrochemical performance of 3.65 and 5.30 mA cm −2 at 1.23 and 1.5 V RHE , respectively, with an applied bias photon-to-current efficiency of 0.68% for the hematite-based photoanodes. This study opens an avenue for designing highly efficient atomic-level engineering on single crystalline semiconductors for feasible photoelectrochemical applications. The achievable photocurrent of hematite, α-Fe 2 O 3 , is typically limited far below its theoretical limit. Here, the authors engineer single Pt atomic sites with surface oxygen vacancies into hematite photoanodes, which leads to enhanced photoelectrochemical water splitting.

Operating fuel cells in alkaline environments permits the use of platinum-group-metal-free (PGM-free) catalysts and inexpensive bipolar plates, leading to significant cost reduction. Of the PGM-free catalysts explored, however, only a few nickel-based materials are active for catalyzing the hydrogen oxidation reaction (HOR) in alkali; moreover, these catalysts deactivate rapidly at high anode potentials owing to nickel hydroxide formation. Here we describe that a nickel–tungsten–copper (Ni 5.2 WCu 2.2 ) ternary alloy showing HOR activity rivals Pt/C benchmark in alkaline electrolyte. Importantly, we achieved a high anode potential up to 0.3 V versus reversible hydrogen electrode on this catalyst with good operational stability over 20 h. The catalyst also displays excellent CO-tolerant ability that Pt/C catalyst lacks. Experimental and theoretical studies uncover that nickel, tungsten, and copper play in synergy to create a favorable alloying surface for optimized hydrogen and hydroxyl bindings, as well as for the improved oxidation resistance, which result in the HOR enhancement. The lack of efficient and cost-effective catalysts for H 2 oxidation reaction (HOR) hinders the application of anion exchange membrane fuel cells. Here, authors report a ternary nickel-tungsten-copper nanoalloy with marked HOR activity and stability that rivals the benchmark platinum catalyst.

Transition metal dichalcogenide materials have been explored extensively as catalysts to negotiate the hydrogen evolution reaction, but they often run at a large excess thermodynamic cost. Although activating strategies, such as defects and composition engineering, have led to remarkable activity gains, there remains the requirement for better performance that aims for real device applications. We report here a phosphorus-doping-induced phase transition from cubic to orthorhombic phases in CoSe 2 . It has been found that the achieved orthorhombic CoSe 2 with appropriate phosphorus dopant (8 wt%) needs the lowest overpotential of 104 mV at 10 mA cm −2 in 1 M KOH, with onset potential as small as −31 mV. This catalyst demonstrates negligible activity decay after 20 h of operation. The striking catalysis performance can be attributed to the favorable electronic structure and local coordination environment created by this doping-induced structural phase transition strategy. Transition metal dichalcogenides represent an exciting class of earth-abundant hydrogen-from-water electrocatalysts, although low efficiencies limit commercialization. Here, authors present a doping strategy to induce a phase transition in cobalt selenide and boost H 2 -evolution performance.

Singlet oxygen has won a great deal of attention to catalysis and biological studies due to its strong oxidizing properties. However, the photosensitizers which require for the generation of singlet oxygen remain inadequate because of their lack of long-wavelength absorption, weak hydrophilicity, and poor biocompatibility. Here, we develop near-infrared laser activated supramolecular photosensitizers (isophthalic acid/layered double hydroxide nanohybrids) for efficient two-photon photodynamic therapy. The singlet oxygen quantum yield of nanohybrid is up to 0.74. Critically, in vitro tests verify the superior anti-cancer properties of nanohybrid with an IC 50 determine to be 0.153 μg mL −1 . The nanohybrids take advantage of the superior tissue penetration of 808 nm laser irradiation and exhibit a dramatically strong ability to ablate tumors in vivo, with extremely low toxicity. This work provides the proof of concept that ultralong-lived triplet excitons can function as two-photon-activated photosensitizers for an effective singlet oxygen generation. Usually, several components are needed for efficient 2-photon photodynamic therapy (PDT). Here, the authors sandwiched carboxylic acids between layered double hydroxide nanosheets to obtain a single-handed biocompatible photosensitizer that generates singlet oxygen in high quantum yield.

Layered molybdenum disulfide has demonstrated great promise as a low-cost alternative to platinum-based catalysts for electrochemical hydrogen production from water. Research effort on this material has focused mainly on synthesizing highly nanostructured molybdenum disulfide that allows the exposure of a large fraction of active edge sites. Here we report a promising microwave-assisted strategy for the synthesis of narrow molybdenum disulfide nanosheets with edge-terminated structure and a significantly expanded interlayer spacing, which exhibit striking kinetic metrics with onset potential of −103 mV, Tafel slope of 49 mV per decade and exchange current density of 9.62 × 10 −3 mA cm −2 , performing among the best of current molybdenum disulfide catalysts. Besides benefits from the edge-terminated structure, the expanded interlayer distance with modified electronic structure is also responsible for the observed catalytic improvement, which suggests a potential way to design newly advanced molybdenum disulfide catalysts through modulating the interlayer distance. Layered molybdenum disulfide is a promising hydrogen evolution catalyst. Here, the authors report a strategy for synthesizing molybdenum disulfide nanosheets with edge-terminated structure and a significantly expanded interlayer spacing and demonstrate their enhanced catalytic activity.

Simultaneously improving the activity and stability of catalysts for anodic oxygen evolution reaction (OER) in proton exchange membrane water electrolysis (PEMWE) remains a notable challenge. Here, we report a chromium-doped ruthenium dioxide with oxygen vacancies, termed Cr 0.2 Ru 0.8 O 2-x , that drives OER with an overpotential of 170 mV at 10 mA cm −2 and operates stably over 2000 h in acidic media. Experimental and theoretical studies show that the synergy of Cr dopant and oxygen vacancy induces an unconventional dopant-mediated hydroxyl spillover mechanism. Such dynamic hydroxyl spillover from Cr dopant to Ru active site changes the rate-determining step from OOH* formation to O 2 formation and thus greatly improves the OER performance. Moreover, the Cr dopant and oxygen vacancy also play a crucial role in stabilizing surface Ru and lattice oxygen in the Ru-O-Cr structural motif. When assembled into the anode of a practical PEMWE device, Cr 0.2 Ru 0.8 O 2-x enables long-term durability of over 200 h at an ampere-level current density and 60 degrees centigrade. Developing highly active and stable anode catalysts for green hydrogen production is crucial but challenging. Here, the authors report a Cr0.2Ru0.8O2-x catalyst with an unconventional dopant-mediated hydroxyl spillover mechanism for high-efficiency proton exchange membrane water electrolysis.

Photoelectrochemical production of ammonia usually suffers from a low solar-to-ammonia efficiency and a high overpotential, which influences the bias-free operation of sustainable photoelectrochemistry. Herein, we realize solar-driven ammonia production from waste nitrate by constructing copper-osmium catalysts deposited on the Sb 2 (S,Se) 3 semiconductor, enabling optimized photo-carrier transport pathways and a beneficial co-adsorption configuration of *NO 3 -H 2 O moieties. The photocathode reaches a photocurrent density of 5.6 mA cm −2 at 0 V RHE with a low onset potential of 0.86 V RHE and a Faradaic efficiency of 96.98% at 0.6 V RHE under AM 1.5 G illumination. We further employ glycerol oxidation reaction on ruthenium doped bismuth oxide catalyst decorated on titanium oxide photoanode, requiring an onset potential of 0.3 V RHE to enable bias-free operation. The unbiased photoelectrochemical system shows Faradaic efficiencies of over 97% for ammonia products and above 77% for glycerol oxidation product under AM 1.5 G illumination. The large-sized photoelectrodes maintain a stability for 24 h without noticeable degradation. Our works indicate that unassisted and stable PEC ammonia production is feasible with in situ glycerol valorization using the photoanode and photocathode. Photoelectrochemical production of ammonia faces challenges with low efficiency and high overpotential. Here, the authors report a bias-free system using copper-osmium and ruthenium-based catalysts, coupled with glycerol oxidation, for solar-driven ammonia production.

The electroreduction of water for sustainable hydrogen production is a critical component of several developing clean-energy technologies, such as water splitting and fuel cells. However, finding a cheap and efficient alternative catalyst to replace currently used platinum-based catalysts is still a prerequisite for the commercialization of these technologies. Here we report a robust and highly active catalyst for hydrogen evolution reaction that is constructed by in situ growth of molybdenum disulfide on the surface of cobalt diselenide. In acidic media, the molybdenum disulfide/cobalt diselenide catalyst exhibits fast hydrogen evolution kinetics with onset potential of −11 mV and Tafel slope of 36 mV per decade, which is the best among the non-noble metal hydrogen evolution catalysts and even approaches to the commercial platinum/carbon catalyst. The high hydrogen evolution activity of molybdenum disulfide/cobalt diselenide hybrid is likely due to the electrocatalytic synergistic effects between hydrogen evolution-active molybdenum disulfide and cobalt diselenide materials and the much increased catalytic sites. There is substantial research into new catalysts for electroreduction of water. Here, the authors report a robust and active molybdenum disulfide/cobalt diselenide hydrogen evolution catalyst with onset potential of 11 mV and Tafel slope of 36 mV per decade, approaching the activity of platinum.

Fast transport of charge carriers in semiconductor photoelectrodes are a major determinant of the solar-to-hydrogen efficiency for photoelectrochemical (PEC) water slitting. While doping metal ions as single atoms/clusters in photoelectrodes has been popularly used to regulate their charge transport, PEC performances are often low due to the limited charge mobility and severe charge recombination. Here, we disperse Ru and P diatomic sites onto hematite (DASs Ru-P:Fe₂O₃) to construct an efficient photoelectrode inspired by the concept of correlated single-atom engineering. The resultant photoanode shows superior photocurrent densities of 4.55 and 6.5 mA cm−2 at 1.23 and 1.50 VRHE, a low-onset potential of 0.58 VRHE, and a high applied bias photon-to-current conversion efficiency of 1.00% under one sun illumination, which are much better than the pristine Fe₂O₃. A detailed dynamic analysis reveals that a remarkable synergetic ineraction of the reduced recombination by a low Ru doping concentration with substitution of Fe site as well as the construction of Ru-P bonds in the material increases the carrier separation and fast charge transportation dynamics. A systematic simulation study further proves the superiority of the Ru-P bonds compared to the Ru-O bonds, which allows more long-lived carriers to participate in the water oxidation reaction. This work offers an effective strategy for enhancing charge carrier transportation dynamics by constructing pair sites into semiconductors, which may be extended to other photoelectrodes for solar water splitting.