The increasing global focus on environmental sustainability has led to a growing emphasis on green purchase behavior. The theory of planned behavior (TPB) is one of the classical theories used to understand individual green purchase behavior from the perspective of psychology. Data are collected through an online survey, and the structural equation modeling (SEM) method is employed for analysis. The research findings demonstrate that consumers’ green purchase intention and environmental knowledge significantly and positively influence green purchase behavior. Moreover, moral obligation plays a partial mediating role in the relationship between green purchase intention and green purchase behavior, as well as in the relationship between environmental knowledge and green purchase behavior. By incorporating moral obligation and environmental knowledge into the TPB framework, this study advances the theoretical understanding of the drivers of green purchase behavior. Furthermore, this study reveals that green purchase intention, compared to environmental knowledge, exerts a greater influence on promoting consumers’ green purchase behavior. This finding underscores the crucial role of consumers’ internal motivation in driving sustainable choice. This study offers valuable implications for the design of green marketing strategies and have the potential to promote environmentally sustainable consumption behavior, thereby contributing to the global sustainability efforts.

Water conservation represents a typical green behavior and a sustainable lifestyle. Understanding residents’ water conservation behaviors is a prerequisite for promoting more water savers. Using the snowball sampling technique, this study conducted a survey on a sample of 532 Chinese residents to investigate their water conservation behavior, i.e., reusing water in daily life. This study aims for examining psychological and knowledge factors on residents’ water conservation behavior in China using binary logistic regression. Results show that over half of the respondents (54%) have the habit of reusing water in their daily lives. Residents with stronger environmental concern and higher level of environmental knowledge are more likely to exhibit household water conservation in China. Additionally, environmental knowledge plays a positive moderating role in the relationship between environmental concern and water conservation behavior. Environmental knowledge serves as a catalyzer that facilitates the transformation from residents’ environmental concern into real water conservation behavior. Among the demographic variables, only income exerts significantly negative effect on residents’ water conservation behavior, and other variables (e.g., age and gender) fail to exert any influence on this behavior. This study contributes to the literature on environmental psychology and concludes with implications for water resource management.