Exploring carbon-based Cu-ZnO catalyst and substitutes for enhanced selective methanol production from CO2: An integrated experimental and computational study

Methanol, produced through the hydrogenation of carbon dioxide, is an essential intermediate compound that plays a crucial function in the production of various organic chemicals. Enhancing the design of copper-containing catalysts for the transformation of CO2 to methanol is a popular strategy in scientific literature, although challenges persist in advancing the efficiency of carbon dioxide transformation and the selectivity of methanol production. This research aims at creating CuZnO-M/rGO (M = Mg, Mn, and Cr) catalysts using an efficient method for selectively converting CO2 to methanol. By optimizing the operational parameters of this system, methanol productivity and CO2 conversion efficiency are enhanced. Under optimal conditions, a CO2 conversion rate of 23.5%, methanol selectivity of 90%, and a space-time yield of 0.47 gMeOH.gcat-1.h-1 were achieved with the CuZnO-MgO (5)/rGO catalyst. These levels were maintained over a 100-h period, demonstrating the stability of the catalyst system. These findings are highly consistent with the density functional theory (DFT) calculations, revealing that the CuZnO-MgO (5)/rGO catalyst possesses a -0.35 eV adsorption energy for CO2 and a favorable reaction pathway with the overpotential of 1.16 V towards methanol production emphasizing the high conversion and selectivity obtained.

Tuning the optoelectronic properties of emerging solar absorbers through cation disorder engineering

Chalcogenide solar absorbers, such as AgBiS2 and kesterites, have gained a resurgence of interest recently, owing to their high stability compared to metal-halide compounds, as well as their rising efficiencies in photovoltaic devices. Although their optical and electronic properties are conventionally tuned through the composition and structure, cation disorder has increased in prominence as another important parameter that influences these properties. In this minireview, we define cation disorder as the occupation of a cation crystallographic site with different species, and the homogeneity of this cation disorder as how regular the alternation of species in this site is. We show that cation disorder is not necessarily detrimental, and can lead to increases in absorption coefficient and reductions in bandgap, enabling the development of ultrathin solar absorbers for lightweight photovoltaics. Focusing on kesterites and ABZ2 materials (where A = monovalent cation, B = divalent cation, and Z is a chalcogenide anion), we discuss how the degree and homogeneity of cation disorder influences the optical properties, charge-carrier transport and photovoltaic performance of these materials, as well as how cation disorder could be tuned and quantified. We finish with our perspectives on the important questions moving forward in making use of cation disorder engineering as a route to achieve more efficient solar absorbers.

AgBiS2@CQDs/Ti nanocomposite coatings for combating implant-associated infections by photodynamic /photothermal therapy

Biofilm-mediated implant-associated infections are one of the most serious complications of implantation surgery, posing a grave threat to patient well-being. Effectively addressing bacterial infections is crucial for the success of implantation procedures. In this study, we prepared a bismuth sulfide silver@carbon quantum dot composite coating (AgBiS2@CQDs/Ti) on a medical titanium surface by surface engineering design to treat implant-associated infections. The photocatalytic/photothermal activity test results confirmed the excellent photogenerated ROS and photothermal properties of AgBiS2@CQDs/Ti under near-infrared laser irradiation. In vitro antibacterial and in vivo anti-infection experiments showed that the coating combined with photodynamic and photothermal therapies to eradicate bacteria and disrupt mature biofilms under 1064 nm laser irradiation. Consequently, AgBiS2@CQDs/Ti shows promise as an implant coating for treating implant-associated infections post-surgery, thereby enhancing the success rate of implantation procedures. This study also provides a new idea for combating implant-associated infections.

Cation-Disorder Engineering Promotes Efficient Charge-Carrier Transport in AgBiS2 Nanocrystal Films

Efficient charge-carrier transport is critical to the success of emergent semiconductors in photovoltaic applications. So far, disorder has been considered detrimental for charge-carrier transport, lowering mobilities, and causing fast recombination. This work demonstrates that, when properly engineered, cation disorder in a multinary chalcogenide semiconductor can considerably enhance the charge-carrier mobility and extend the charge-carrier lifetime. Here, the properties of AgBiS2 nanocrystals (NCs) are explored as a function of Ag and Bi cation-ordering, which can be modified via thermal-annealing. Local Ag-rich and Bi-rich domains formed during hot-injection synthesis are transformed to induce homogeneous disorder (random Ag-Bi distribution). Such cation-disorder engineering results in a sixfold increase in the charge-carrier mobility, reaching ≈2.7 cm2 V-1 s-1 in AgBiS2 NC thin films. It is further demonstrated that homogeneous cation disorder reduces charge-carrier localization, a hallmark of charge-carrier transport recently observed in silver-bismuth semiconductors. This work proposes that cation-disorder engineering flattens the disordered electronic landscape, removing tail states that would otherwise exacerbate Anderson localization of small polaronic states. Together, these findings unravel how cation-disorder engineering in multinary semiconductors can enhance the efficiency of renewable energy applications.

Mixed AgBiS2 nanocrystals for photovoltaics and photodetectors

Heavy-metal-free colloidal nanocrystals are gaining due attention as low-cost, semiconducting materials for solution-processed optoelectronic applications. One common limitation of such materials is their limited carrier transport and trap-assisted recombination, which impede the performance of thick photoactive layers. Here we mix small-size and large-size AgBiS2 nanocrystals to judiciously favour the band alignment in photovoltaic and photodetector devices. The absorbing layer of these devices is fabricated in a gradient fashion in order to maximise charge transfer and transport. We implement this strategy to fabricate mixed AgBiS2 thin film solar cells with a power conversion of 7.3%, which significantly surpasses the performance of previously reported devices based on single-batch AgBiS2 nanocrystals. Additionally, this approach allows us to fabricate devices using thicker photoactive layers that show lower dark currents and external quantum efficiencies exceeding 40% over a broad bandwidth - covering the visible and near infrared range beyond 1 μm, thus unleashing the potential of colloidal AgBiS2 nanocrystals in photodetector applications.

Atomic periodic engineering enabled ultrathin high-efficiency AgBiS2 solar cells

The periodic engineering of AgS6 and BiS6 octahedrons is demonstrated. The modulated AgBiS2 achieves a spectroscopic limited maximum efficiency as high as 29.7% with an ultrathin thickness of 100 nm.

AgFeS2 nanoparticles as a novel photothermal platform for effective artery stenosis therapy

Ternary I-III-VI2 semiconductors usually have narrow band gaps and large absorption coefficients arising from the unique characteristics of their outer-d valence electrons, which are intimately connected with the photothermal conversion properties. AgFeS2 is known as one such material that has the potential to absorb near-infrared light. In this work, we utilized density functional theory (DFT) calculations to evaluate the electronic structure and optical absorption properties of AgFeS2. Strong absorptions were predicted over a wide Vis-NIR region due to the localized 3d electron of Fe atoms, which agree quite well with the UV-Vis-NIR spectra measured by experiment. The as-prepared AgFeS2 nanoparticles were then modified with mPEG-DSPE, an efficient photothermal agent for artery stenosis therapy. Its photothermal conversion effect has been systematically studied, indicating the potential for causing the hyperthermia of macrophages, an essential part of the artery inflammation response. More importantly, both in vitro cell experiments and in vivo mouse-model studies show that the induction of hyperthermia in artery stenosis by using AgFeS2 nanoparticles is safe and effective when injected at a very low concentration. This study provides a novel photothermal platform derived from the inheritability of bandgap structure and also promotes the process of artery inflammation and stenosis therapy.

Cation Disorder and Local Structural Distortions in AgxBi1-xS2 Nanoparticles

By combining X-ray absorption fine structure and X-ray diffraction measurements with density functional and molecular dynamics simulations, we study the structure of a set of Ag_xBi_1−xS₂ nanoparticles, a materials system of considerable current interest for photovoltaics. An apparent contradiction between the evidence provided by X-ray absorption and diffraction measurements is solved by means of the simulations. We find that disorder in the cation sublattice induces strong local distortions, leading to the appearance of short Ag–S bonds, the overall lattice symmetry remaining close to hexagonal.

Effect of cationic disorder on the energy generation and energy storage applications of NixCo3−xS4 thiospinel

Thiospinels show interesting catalytic and energy storage applications, however, the cationic disorder can have major influence on the energy generation and/or energy storage applications.