Economic resilience represents a nation’s capacity to withstand external shocks, quicken economic recovery, and attain sustainable development. Can Pilot Free Trade Zones (PFTZs), as testing fields for China’s institutional openness, boost the economic resilience of host cities? This study empirically investigates the impact and mechanisms of establishing PFTZs on urban economic resilience. It does so by building overlapping Difference-in-Differences (DID), Propensity Score Matching DID (PSM-DID), and spatial DID models using panel data across 284 cities in China from 2007 to 2021. It is found that establishing PFTZs significantly promotes urban economic resilience, and PFTZs largely achieve this by increasing population density, consumer demand, and economic growth in host cities. Spatial heterogeneity analysis reveals that PFTZs in North, East, Central, and South China notably enhance urban economic resilience, whereas those in Northeast, Southwest, and Northwest China do not. Regarding spatial spillover effects, the establishment of PFTZs has a beneficial impact on the economic resilience of nearby cities within a radius of 100 km to 400 km. The impacts become stronger as the distance grows, peaking at a radius of 400 km. This research offers important policy implications for promoting the establishment of PFTZs, unlocking the benefits of institutional openness, and strengthening urban economic resilience.

Reducing the carbon intensity of well-being (CIWB) is essential for advancing environmental sustainability and socio-economic development. The expansion of digital service trade has emerged as a novel engine of global economic growth and a promising pathway for pollution reduction and carbon mitigation. This study investigates the nonlinear impact of digital service trade on CIWB, identifying an inverted U-shaped relationship—initially increasing CIWB, then reducing it beyond a certain threshold. In the financial digital service trade sector, this effect is mediated by energy structure transition, whereas in the technology-intensive sector, it is driven by green technological innovation. In contrast, digital service trade in the insurance, pension, and audiovisual sectors directly suppresses CIWB. Moreover, rising public environmental awareness helps leverage and strengthen the inhibitory effect of digital service trade on CIWB. Regionally, except for North America (which displays a consistently inhibitory effect), Asia, Africa, Europe, and Oceania reflect patterns similar to the overall sample. In regions with higher economic and internet development levels, the inverted U-shaped curve is steeper, and its turning point is located further to the left. Temporally, the relationship mirrors the full-sample patterns prior to the enforcement of the Paris Agreement, while an inhibitory effect emerges afterward. These findings offer policy implications for achieving the United Nations’ 2030 Sustainable Development Goals.

Against the backdrop of rapid development in marine engineering, the construction industry faces practical challenges, such as water scarcity, limited availability of natural river sand, and high raw material transportation costs. This has led to an increasing demand for resource-efficient concrete production technologies and improved construction economic efficiency. Seawater–sea-sand concrete (SWSSC) offers a locally sourced solution that effectively reduces the construction sector’s overreliance on freshwater and river sand, lowers material transportation costs for coastal infrastructure projects, and supports marine engineering and infrastructure development along the Belt and Road Initiative. However, existing research lacks systematic organization and visualized quantitative analysis. Utilizing the CiteSpace 7.0.R0 knowledge graph analysis software, this study selects 982 relevant papers published in the Web of Science (WOS) Core Collection between 2016 and 2025 as the sample. By employing analytical methods—including annual publication volume statistics, collaboration networks among researchers, keyword co-occurrence patterns, and temporal evolution charts—we systematically delineate the overall research landscape, distribution of key research institutions, trends in research hotspots, and future frontier directions in this field. The analysis results indicate that: (1) The total number of publications in the global seawater–sand concrete field has been increasing year by year. From 2016 to 2018, it was the basic exploration period, with an average annual publication volume of less than 10. From 2019 to 2021, it was the deepening and expansion period, with research expanding from the performance of a single material to material modification and structural application. From 2022 to 2025, it was the rapid prosperity period, with the publication volume reaching its peak in 2024–2025 (208 articles and 203 articles), and the publication volume continued to rise. (2) China ranks first globally with 798 publications, but its centrality in international cooperation networks is only 0.24, reflecting low overall collaboration density and loose partnerships between institutions and authors, without the formation of cross-institutional core research teams with global leadership. (3) Research hotspots in this field primarily focus on material properties, durability characteristics, and mechanical strength, among which FRP reinforcement systems serve as a bridge for interdisciplinary research bridging material fundamentals and engineering applications, representing a key research branch. (4) From the perspective of evolutionary trends, the field exhibits three major developmental shifts from macroscopic mechanical performance characterization to in-depth investigation of microscopic damage mechanisms, from single-material studies to composite structural systems, and from short-term laboratory accelerated testing to full life-cycle performance evaluation, with the low-carbon potential of seawater–sand concrete increasingly becoming a prominent research focus. Therefore, this paper advocates strengthening international and inter-institutional academic collaboration, fostering multidisciplinary innovation, and prioritizing breakthroughs in key areas, such as large-scale intelligent performance prediction, long-term performance database development, and digital-twin-based operation and maintenance management, to facilitate the transition of seawater–sand concrete technology toward efficient, low-carbon, safe, and intelligent engineering applications.