The pH and electric responsive composite hydrogels were prepared by in situ polymerization in the presence of graphene oxide (GO). Their structure and properties were characterized by scanning electron microscopy, Raman microscopy and mechanical testing. The results indicate that the GO is evenly dispersed in the composite hydrogels and the mechanical properties of the GO based composite hydrogels are significantly improved. Most importantly, the composite hydrogels were responsive to external stimuli such as pH and electric field.

This study estimates China’s methane (CH₄) emissions from 43 specific emission sources in 2020 and projects future trends through 2050 under two scenarios: Current Legislation (CLE) and Maximum Technically Feasible Reduction (MFR). The analysis utilises the Greenhouse gas and Air pollution Interactions and Synergies (GAINS) model methane framework, incorporating updated province-level activity data to capture the pronounced regional heterogeneity inherent in emission profiles and mitigation capacities. The results reveal a national CH₄ budget of 1114 MtCO₂e in 2020, with the energy sector (59%) and agriculture (28%) emerging as the primary contributors. A substantial technical mitigation potential is identified; by 2050, emissions could be curtailed by up to 48% relative to the CLE scenario, representing a 46% reduction from 2020 levels. The energy and waste sectors emerge as the primary contributors to this potential. Specifically, coal mining CH₄ abatement constitutes 58% of the energy sector’s total reduction potential, while enhanced solid waste management accounts for 97% of the mitigation within the waste sector. Key measures include ventilation air methane (VAM) oxidation and pre-mining degasification, as well as anaerobic digestion and recovery and utilization for energy use. Owing to regional disparities in hydrothermal conditions (representing the combined influence of temperature and moisture), demographic status, economic development, the most effective mitigation strategies vary across provinces. For example, pre-mining degasification and VAM oxidation are most impactful in major coal-producing regions such as Shanxi, Inner Mongolia, and Shaanxi. In contrast, anaerobic digestion, recovery and utilization, and waste incineration play a dominant role in more economically developed and densely populated provinces such as Jiangsu, Shandong and Zhejiang. By delineating region-specific technological priorities, this study quantifies the maximum technical mitigation potential for China and offers guidance for other nations facing similar mitigation challenges.

To response to the urgent need for anthropogenic methane mitigation, the State Council of China issued the Methane Emissions Control Action Plan in 2023, prioritizing the strategic deployment of advanced emission control technologies across the energy, waste, and agricultural sectors. Despite its significance, a granular, measure-by-measure evaluation of this national policy remains absent in the current literature. This study utilizes 17 provinces in Northern China as a representative case to quantitatively assess the implications of 13 key mitigation actions. Employing the Greenhouse gas and Air pollution Interactions and Synergies model methane framework and scenario analysis, we find that the full implementation of these measures could yield a 21% reduction in regional methane emissions by 2050 relative to 2020 levels. Five critical technical levers - ventilation air methane (VAM) oxidation and utilization, landfill gas management, pre-mining drainage, leak detection and repair programs, and waste recycling – collectively account for 93% of the total mitigation potential. However, the efficacy of specific mitigation measures exhibits significant provincial heterogeneity. Energy-intensive hubs, such as Shanxi, Shaanxi, Inner Mongolia, benefit predominantly from coal mining methane related interventions (VAM oxidation and pre-mining drainage), whereas landfill gas management and waste recycling are pivotal are pivotal for economically developed and densely populated regions like Beijing and Shandong. By identifying province-tailored mitigation portfolios, our findings provide high-resolution guidance for optimizing methane governance in China and offer a replicable evaluation framework for other nations striving to achieve ambitious climate targets.