Conjugated Phosphonic Acids Enable Robust Hole Transport Layers for Efficient and Intrinsically Stable Perovskite Solar Cells

High efficiency and long-term stability are the prerequisites for the commercialization of perovskite solar cells (PSCs). However, inadequate and non-uniform doping of hole transport layers (HTLs) still limits the efficiency improvements, while the intrinsic instability of HTLs caused by ion migration and accumulation is difficult to be addressed by external encapsulation. Here it is shown that the addition of a conjugated phosphonic acid (CPA) to the Spiro-OMeTAD benchmark HTL can greatly enhance the device efficiency and intrinsic stability. Featuring an optimal diprotic-acid structure, indolo(3,2-b)carbazole-5,11-diylbis(butane-4,1-diyl) bis(phosphonic acid) (BCZ) is developed to promote morphological uniformity and mitigate ion migration across both perovskite/HTL and HTL/Ag interfaces, leading to superior charge conductivity, reinforced ion immobilization, and remarkable film stability. The dramatically improved interfacial charge collection endows BCZ-based n-i-p PSCs with a champion power conversion efficiency of 24.51%. More encouragingly, the BCZ-based devices demonstrate remarkable stability under harsh environmental conditions by retaining 90% of initial efficiency after 3000 h in air storage. This work paves the way for further developing robust organic HTLs for optoelectronic devices.

Dual-Functional Ru/Ni-B-P Electrocatalyst Toward Accelerated Water Electrolysis and High-Stability

Development of advanced electrocatalysts for the green hydrogen production by water electrolysis is an important task to reduce the climate and environmental issues as well as to meet the future energy demands. Herein, Ru/Ni-B-P sphere electrocatalyst is demonstrated by a combination of hydrothermal and soaking approaches, meeting the industrial requirement of low cell voltage with stable high-current operation. The Ru/Ni-B-P sphere catalyst demonstrates low overpotentials of 191 and 350 mV at 300 mA cm-2 with stable high current operation, ranking it as one of the best oxygen evolution reaction (OER) electrocatalysts. The bifunctional 2-E system demonstrates a low cell voltage of 2.49 V at 2000 mA cm-2 in 6 m KOH at 60 °C of harsh industrial operation condition. It also demonstrates outstanding stability with continuous 120 h (5 days) CA operation at 1000 mA cm-2. Further, the hybrid configuration of Ru/Ni-B-P || Pt/C being paired with the conventional benchmark electrode demonstrates a record low 2-E cell voltage of 2.40 V at 2000 mA cm-2 in 6 m KOH and excellent stability at high current of 1500 mA cm-2 under industrial operational condition.

In-situ fabrication of Cr doped FeNi LDH on commercial stainless steel for oxygen evolution reaction

Commercial stainless steel has attracted increasing interest due to their rich content in transition metal elements and corrosion resistance properties. In this work, we design a facile and rapid route to in-situ fabricate the Cr doped FeNi layered double hydroxides nanosheets (LDHs) on modified stainless steel (Cr-FeNi LDH @ ESS) under ambient condition.The ultra small scaled 2D structure only around 20 nm diameter and metal ions with multivalent oxidation state were observed on the in situ fabricated LDHs, which provides high active area and active sites and thus promote excellent oxygen evolution reaction (OER). The Cr-FeNi LDH @ESS electrocatalysts exhibit an over potential of 280 mV at 10 mA cm-2 and achieves a Tafel slope of 44 mV dec-1 for OER in the 1.0 M KOH aqueous solution. We anticipate that the operating strategy of our system may promote the development of commercial non-precious productions as the efficient electrocatalysts for energy storage and conversion.

Transition Metal Catalysts for Atmospheric Heavy Metal Removal: A Review of Current Innovations and Advances

Atmospheric heavy metal pollution presents a severe threat to public health and environmental stability. Transition metal catalysts have emerged as a potent solution for the selective capture and removal of these pollutants. This review provides a comprehensive summary of current advancements in the field, emphasizing the efficiency and specificity of nanostructured transition metals, including manganese, iron, cobalt, nickel, copper, and zinc. Looking forward, we delve into the prospective trajectory of catalyst development, underscoring the need for materials with enhanced stability, regenerability, and environmental compatibility. We project that advancements in computational materials science, nanotechnology, and green chemistry will be pivotal in discovering innovative catalysts that are economically and environmentally sustainable. The integration of smart technologies for real-time monitoring and adaptive control is anticipated to revolutionize heavy metal remediation, ensuring efficient and responsive pollution abatement strategies in the face of evolving industrial scenarios and regulatory landscapes.

Engineering the Structural Defects of Spinel Oxide Nanoneedles by Doping of V for a Highly Efficient Oxygen Evolution Reaction

Rational design of multi-structural defects in the transition-metal oxides is a very alluring and challenging strategy to significantly improve its oxygen evolution reaction (OER) performance. Herein, a simple and promising element doping approach is demonstrated to fabricate a poor-crystalline V-doping CuCo2O4 (V-CuCo2O4) nanoneedle with rich oxygen vacancies (Vo), partially amorphous phase, and Co2+ defects on the carbon fiber (CF) (V-CuCo2O4/CF). The results indicate that the V doping could further weaken the crystallinity of V-CuCo2O4, providing the thoroughfares for the convenience of electrolyte penetration and the exposure of active sites. Meanwhile, [CoO6] octahedron in the V-CuCo2O4 lattice is gravely distorted due to a strong electronic interaction between the doped V and Co atoms, creating more Co2+ active species. With the merits of these multiple structural defects, V-CuCo2O4/CF exhibits rich active sites, and its intrinsically electrocatalytic activity is significantly enhanced. The optimized V-CuCo2O4/CF electrocatalyst has a significantly enhanced OER activity with a required low overpotential of ∼204 and ∼246 mV at a current density of 100 and 300 mA cm-2, respectively, a small Tafel slope of 40.7 mV dec-1, and excellent stability in an alkaline medium. Furthermore, the results from the projected partial density of states calculation not only demonstrate that the 3-fol-coordinated Co near Vo bonded with Cu and V sites (Cu-Co(surf-Vo)-V) exhibits an enhanced electronic transfer activity but also reveal that the doped V could protect the Co sites from the deactivation by intermediates overbinding on the V sites. This work provides new insights into structure engineering of spinel phase copper cobaltite, resulting in significantly boosting electrocatalytic OER activity.

Tungsten-Based Nanocatalysts: Research Progress and Future Prospects

The high price of noble metal resources limits its commercial application and stimulates the potential for developing new catalysts that can replace noble metal catalysts. Tungsten-based catalysts have become the most important substitutes for noble metal catalysts because of their rich resources, friendly environment, rich valence and better adsorption enthalpy. However, some challenges still hinder the development of tungsten-based catalysts, such as limited catalytic activity, instability, difficult recovery, and so on. At present, the focus of tungsten-based catalyst research is to develop a satisfactory material with high catalytic performance, excellent stability and green environmental protection, mainly including tungsten atomic catalysts, tungsten metal nanocatalysts, tungsten-based compound nanocatalysts, and so on. In this work, we first present the research status of these tungsten-based catalysts with different sizes, existing forms, and chemical compositions, and further provide a basis for future perspectives on tungsten-based catalysts.

Shape controllable MoS2 nanocrystals prepared by the single precursor route for electrocatalytic hydrogen evolution

MoS₂ has attracted great attention as a prospective electrocatalyst for generating hydrogen via water electrolysis due to its abundant and inexpensive sources. However, bulk MoS₂ has weak electrocatalytic activity because of its low electrical conductivity and few edge-active sites. Controllable synthesis of MoS₂ with ultrasmall size or complex morphology may be an available strategy to boost its conductivity and edge-active sites. Herein, a facile single-precursor strategy was developed to prepare nanoscale MoS₂ with various morphologies, including quantum dots, nanorods, nanoribbons, and nanosheets. In-depth studies show that the formation of MoS₂ with various shapes is determined by both kinetic and thermodynamic factors such as reaction time and temperature. Electrocatalytic tests reveal that MoS₂ quantum dots have high electrocatalytic performance with a low overpotential of 255 mV and a small Tafel slope of 66 mV dec⁻¹ due to the abundant exposed active edges and excellent intrinsic conductivity.

A facile single-precursor route was designed for the synthesis of shape- and size-controllable MoS₂ nanocrystals, including MoS₂ QDs, nanorods, nanoribbons, and nanosheets. Among them, MoS₂ QDs exhibit higher electrocatalytic activity in HRE.

In situ templating synthesis of mesoporous Ni–Fe electrocatalyst for oxygen evolution reaction

Low-cost and efficient electrocatalysts with high dispersion of active sites and high conductivity are of high importance for oxygen evolution reaction (OER). Herein, we use amorphous mesoporous fumed silica (MFS) as a skeleton material to disperse Ni²⁺ and Fe³⁺ through a simple impregnation strategy. The MFS is in situ etched away during the OER process in 1 M KOH to prepare a stable mesoporous Ni–Fe electrocatalyst. The high specific surface area and abundant surface silanol groups in the mesoporous fumed silica afford rich anchor sites for fixing metal atoms via strong chemical metal–oxygen interactions. Raman and XPS investigations reveal that Ni²⁺ formed covalent bonds with surface Si–OH groups, and Fe³⁺ inserted into the framework of fumed silica forming Fe–O–Si bonds. The mesoporous Ni–Fe catalysts offer high charge transfer abilities in the OER process. When loaded on nickel foam, the optimal 2Ni1Fe-MFS catalyst exhibits an overpotential of 270 mV at 10 mA cm⁻² and a Tafel slope of 41 mV dec⁻¹. Notably, 2Ni1Fe-MFS shows a turnover frequency value of 0.155 s⁻¹ at an overpotential of 300 mV, which is 80 and 190 times higher than that of the state-of-the-art IrO₂ and RuO₂ catalysts. Furthermore, 2Ni1Fe-MFS exhibits 100% faradaic efficiency, large electrochemically active surface area, and good long-term durability, confirming its outstanding OER performance. Such high OER efficiency can be ascribed to the synergistic effect of high surface area, dense metal active sites and interfacial conductive path. This work provides a promising strategy to develop simple, cost-effective, and highly efficient porous Ni–Fe based catalysts for OER.

A stable mesoporous Ni–Fe–O electrocatalyst with high OER efficiency is constructed using mesoporous fumed silica as a template.