Arsenic (As) contamination in groundwater is a worldwide concern for drinking water safety. Environmental changes and anthropogenic activities are making groundwater vulnerable in Pakistan, especially in Southern Punjab. This study explores the distribution, hydrogeochemical behavior, and pathways of As enrichment in groundwater and discusses the corresponding evolution mechanism, mobilization capability, and health risks. In total, 510 groundwater samples were collected from three tehsils in the Punjab province of Pakistan to analyze As and other physiochemical parameters. Arsenic concentration averaged 14.0 μg/L in Vehari, 11.0 μg/L in Burewala, and 13.0 μg/L in Mailsi. Piper-plots indicated the dominance of Na⁺, SO₄²⁻, Ca²⁺, and Mg²⁺ ions in the groundwater and the geochemical modeling showed negative saturation indices with calcium carbonate and salt minerals, including aragonite (CaCO₃), calcite (CaCO₃), dolomite (CaMg(CO₃)₂), and halite (NaCl). The dissolution process hinted at their potential roles in As mobilization in groundwater. These results were further validated with an inverse model of the dissolution of calcium-bearing mineral, and the exchange of cations between Ca²⁺ and Na⁺ in the studied area. Risk assessment suggested potential carcinogenic risks (CR > 10⁻⁴) for both children and adults, whereas children had a significant non-carcinogenic risk hazard quotient (HQ > 1). Accordingly, children had higher overall health risks than adults. Groundwater in Vehari and Mailsi was at higher risk than in Burewala. Our findings provide important and baseline information for groundwater As assessment at a provincial level, which is essential for initiating As health risk reduction. The current study also recommends efficient management strategies for As-contaminated groundwater.

Reasonable design of electrocatalyst based on abundant earth elements is of great importance for sustainable energy use. Transition metal nitrogen doped carbon (TM-N/C) materials demonstrate excellent catalytic activity. However, there is still a lack of comprehensive understanding of these TM-N/C-systems. Herein, we have developed an effective approach to develop highly active and stable Cu promoted N-doped carbon (Cu-N/C) catalysts. The impacts of copper doping and temperature of pyrolysis on catalytic performance have been studied. The Cu-NC-800 catalysts exhibited excellent catalytic activity and stability with an onset potential (E_o) of 0.99 V and half-wave potential (E_1/2) of 0.85 V. It also shows strong the long-term stability. The synergistic effect between Cu (II)-N ligand and Cu⁰ nanoparticles is high, the active center is small, the transfer of mass is rapid, and the electrocatalytic efficiency is increased. The findings showed that the non-noble metal-based catalyst’s bifunctional oxygen electrode activities prepared in this study were as high as those of commercial oxygen-based, noble metal catalysts.

Catalysts for slow oxygen reduction reaction (ORR) are of great importance for long-term operation and wide application for the cathode of proton exchange membrane fuel cells (PEMFCs). Herein, an efficient approach used for the rational synthesis of an effective ORR electrocatalyst by encapsulating Pt nanoparticles with ultra-low content (0.5, 1.0, 1.5 wt.% Pt) on the surface of a copper-based organic metal frame (Cu-MOF-74) and then carbonized at 900 °C, for the first time. The catalyst Pt_1%/Cu/NC-900 from the series of prepared catalysts exhibits a highly efficient ORR activity with an onset potential (E_o) 1.01 V vs RHE and half-wave potential (E_1/2) 0.88 V vs RHE compare to commercial Pt/C (E_o 0.96 V and E_1/2 0.86 V vs RHE). It has also displayed excellent long-term stability in an alkaline solution. The Pt_1%/Cu/NC-900 performance and stability are dramatically improved, which may be attributed to the interaction of Pt with Cu and carbon carriers. Such an architecture provides an efficient approach for direct application of MOFs to electrocatalysts. To the best of our knowledge, this is the first time we have used bimetallic Pt-Cu catalysts with ultra-low Pt contents for the ORR in the alkaline solution with superior activity than commercial Pt/C.

Developing new materials that can enhance the efficiency of energy conversion and storage systems is critical to meeting the rising energy demand of low-carbon economies. Mesoporous materials have the advantages of large specific surface area and multiple channels, which can increase efficiency and flexibility in terms of energy and power density. An active catalyst for oxygen reduction reaction (ORR) based on Pt–Cr nanoparticles with ultralow Pt content (0.90 wt%) has been studied in this paper. In contrast, electrocatalyst Pt/Cr/NPC-900 exhibited an ORR activity with onset potential ( E _o ) of 1.01 V vs. RHE in an alkaline solution that was superior to commercial Pt/C (20 wt%) (0.96 V vs. RHE). The presence of metal oxides and optimal Pt content enhanced the ORR activity. Therefore, the synergistic effect of the high surface area increased charge transfer, and excellent structural stability can achieve significant ORR efficiency, which is conducive to excellent activity. These findings provide a new perspective for economical and practical ORR electrocatalysts to be designed and synthesized rationally.

Nanocomposites of polyvinylidene fluoride (PVDF) with dimensional (1D) cobalt oxide (Co₃O₄) and f-MWCNTs were prepared successfully by the solution casting method. The impact of 1D Co₃O₄ filler and 1D Co₃O₄/f-MWCNTs co-fillers on the structural, thermal, and electrical behavior of PVDF were studied. The crystal structural properties of pure PVDF and its nanocomposite films were studied by XRD, which revealed a significant enhancement of β-phase PVDF in the resulting nanocomposite films. The increase in β-phase was further revealed by the FTIR spectroscopic analysis of the samples. TG, DTA, and DSC analyses confirmed an increase in thermal stability of PVDF with the addition of nano-fillers as well as their increasing wt.%. From impedance spectroscopic studies, it was found that the DC conductivity of PVDF increases insignificantly initially (up to 0.1 wt.% of nano-fillers addition), but a significant improvement in DC conductivity was found at higher concentrations of the nano-fillers. Furthermore, it was observed that the DC conductivity decreases with frequency. The increase in DC conductivity corresponded to the strong interactions of nano-fillers with PVDF polymer chains.