RESEARCH TRENDS OF GREEN PURCHASING BEHAVIOUR: A DECADE SYSTEMATIC REVIEW

Natural resources are the World's assets that are useful for ensuring the future of mankind so that the topic of environmental protection has become a global concern. Using environmentally friendly products will certainly minimize the negative impact on the environment. There has been a rapid growth in green marketing research and its impact on customer behavior in recent years which is interesting to study. This article aims to find out: (1) How literature in the field of green purchasing behaviour has grown? (2) What is the next area of GLB research is lacking? (3) Where is the country that has done the most research on GPB? The review was performed using Scopus for the period 2013 to 2023 and uses VOSviewer as auxiliary software and uses Publish or Perish to help group data. The final sample comprised is 86 articles were found and sorting. The result shows that 2022 was the peak of publication. These values led to the identification of 43 items and 4 clusters. This study has added to existing knowledge and understanding of important and recent factors in the adoption of green purchase behavior.


Introduction
Natural resources are assets of the World that include air, water, soil, and all living things, whether they are renewable or not.They are important for maintaining the survival of humanity (Costanza & Daly, 1992).In present times, humans have undertaken more resource-consuming activities and made the topic of environmental protection a global concern.Nearly 70% of the greenhouse effect footprint depends on the choice of consumers for the products they choose, use and how they dispose of them in a sustainable manner (White et al., 2019).The conflict between Russia and Ukraine caused an increase in energy prices up to 4 times because Russia is the main supplier of gas to Europe (Jagtap et al., 2022).This shows clearly that the World is increasingly in need renewable energy sources to ensure the life of future generations.
The El-Nino phenomenon or warming sea surface temperature that occurs in the central and eastern Pacific Ocean makes the 2023 dry season drier than the previous 3 years (BMKG, 2023).The impact of this phenomenon will result in drought, which will lead to land in the agricultural sector.In addition, this dry condition will trigger forest fires which can cause haze and impact the quality of the environment, economy, social and public health.The El-Nino problem that makes this drought worse is the problem of air pollution.Based on data from the Air Quality Index (2023), Jakarta, the capital city of Indonesia is in first place with the worst air quality in the world, reaching 169.Indonesia seems to be able to follow China's, which has succeeded in reducing the amount of air pollution in its country by up to 40% within 7 years by reducing coal-fired power plants, power plants that switch to natural gas, add renewable energy power plants, limit private vehicles and focus on big cities.
In 2023, the importance of green marketing has increased significantly as consumers are paying more attention to the environmental impact of their purchases.Nevertheless, companies encounter various difficulties when promoting their products or services as eco-friendly.Green marketing, which is commonly referred to as "sustainable marketing" or "eco-friendly marketing", is carried out by companies by providing services and products that pay attention to advantages and values from the environment (Kaur et al., 2022).Companies see that green marketing has become very important because it provides competitive advantage, improves organizational performance, increases customer satisfaction levels, and improves green corporate image (GCI) (Bathmanathan & Rajadurai, 2019).The company also responds to consumers who are sensitive to the issue of sustainable consumption, so the company focuses on offering environmentally friendly products and services.
The use of environmentally friendly products will certainly minimize the negative impact on the environment.Environmentally friendly products are raw materials that are friendly for the environment, free of pesticides and chemical fertilizers, without toxic ingredients, limiting the use of genetically modified organisms and using environmentally friendly packaging.Purchasing environmentally friendly products (green products) by consumers so that they can use resources optimally and are environmentally friendly refers to the notion of green purchasing (Sheng et al., 2019).There are many studies that examine consumer green purchase behavior and show results in the form of factors that influence it.Research using a Systematic Literature Review on 53 papers in 2000-2014 conducted by Joshi & Rahman (2015) shows that the factors that make green product purchase behavior are due to environmental concerns and product functional attributes.According to research Zhang & Dong (2020), the most dominant factor for consumers to purchase green is due to individual factors consisting of psychological aspects, habits and lifestyle, and socio-demographics.Indeed, there has been a rapid growth in green marketing research and its impact on customer behavior in recent years, but there is still a lack of papers explaining the conceptual clarity of the relationship between the two (Skackauskiene & Vilkaite-Vaitone, 2023).After researchers conducted a search for journals using the Publish or Perish application, they still found limitations in research that examined the relationship between green marketing and green purchase behavior.Green purchase behavior is also still lack of research, where the VOSviewer application shows a less bright color.The purpose of this research is to see: (1) How literature in the field of green purchasing behaviour has grown?(2) What is the next area of GLB research is lacking?(3) Where is the country that has done the most research on GPB?

Methods
To produce a comprehensive set of guidelines on conducting a systematic literature review in the field of management, Tranfield et al (2003) suggested a three-step approach: planning, execution of the review, and focuses on reporting and disseminating the findings.This recommended methodology has been utilized for the current analysis.

Planning the SLR
The quantitative method of Systematic Literature Review was chosen for analyzing scientific production in green purchase marketing.We conducted a comprehensive SLR (Systematic Literature Review) by entering the designated title in the Scopus database.Subsequently, we utilized a systematic approach to gather a sample set of research papers by adhering to specific inclusion and exclusion criteria.To accomplish our goals, the specific terms "Green Purchase Behaviour" and "Green Purchasing Behaviour" were employed for searching the title of the scholarly literature.
To ensure the integrity of the review, we utilized the Scopus database, as it provides a comprehensive collection of scientific research encompassing over 18,000 publications from over 5,000 renowned international publishers across various disciplines, including science, technology, medicine, social sciences, arts, and humanities.We chose Scopus due to its extensive archive of articles and the inclusion of a wider range of journals compared to alternatives like Web of Science.Furthermore, Scopus offers additional functionalities, such as visualization, analysis, and comparison tools, which enable researchers to conduct detailed descriptive analyses.While conducting our research, we excluded Google Scholar due to its inaccuracies in citation analysis and insufficient search filters for the purposes at hand (Gregorio et al., 2018).

Executing the SLR The
To retrieve data related to Scopus indexed journals is by utilizing a reference management tool called Publish or Perish.This program is designed to simplify literature research for scholars.It offers a wide range of journal search engines, including Scopus.Researchers can also specify the time period, keywords, and article types that align with their interests, allowing them to effectively narrow down the list of relevant journals.A journal search was carried out using the Publish or Perish application from 2013-2023 indexed by Scopus with the titles "Green Purchase Behavior" and get 87 papers, while "Green Purchasing Behavior" title get 49 papers.Then reduction is carried out by entering the data into excel, only looking for journals, in English, only relevant abstracts, and no duplication.A final total of 86 publications was obtained.Journal data obtained from using the Publish or Perish application is stored in the form: research information system (.ris) and comma-separated value formats (*.csv).
In this study, the researcher used the Vosviewer application which is able to display journal reference data into a map that links the relationship between one term under study and another term.Vosviewer software is primarily used for the purpose of visually representing and analyzing patterns in networks.It categorizes the visualizations into three types: network visualization, overlay visualization, and density visualization. 1. Network Visualization: This aspect of Vosviewer focuses on displaying the strength and relationship dynamics within a network.It involves mapping the connections between various entities, such as research terms, individuals, or organizations.By visualizing these connections, the software helps identify any clusters or groups within the network and identifies nodes with a higher number of connections, indicating their importance or influence.2. Overlay Visualization: Overlay visualization entails adding additional information to the underlying network map.It leverages the historical aspect by highlighting changes in the research patterns over time.3. Density Visualization: The year of research publication is typically used as an overlay, providing insights into how certain topics or disciplines have evolved or gained prominence.This visual aid helps in understanding long-term trends and patterns.

Results and Discussion
In this section, the findings from the analysis of the bibliography, content analysis to classify the findings according to the study's theme, and analysis of publication patterns and key contributions are discussed.

The Number of Papers Published per Year
Over the past decade, the significance of research topics within the academic realm has become increasingly apparent.During the SLR execution stage, a total of 86 scholarly articles were identified.In general, there has been a steady growth in the number of annual publications related to green purchase marketing.This trend suggests that 2022 will be the year with the highest publication count, with 16 journals on this topic indexed on Scopus.Figure 1 illustrates trends in the metrics literature over the last 10 years.The number of articles increased to 6 in 2016 and in 2023, the number of published articles decreased slightly, it must be considered that the year is not over yet and more articles are expected to be published on the topic.

Publication of Journal
Over the previous ten years, Green Purchase Behavior research has been published in 86 scholarly journals.The Journal of Cleaner Production is the most popular source, accounting for 9.30% of all journals with eight articles, followed by the International Journal of Environmental Research and Public Health with five articles.The remaining publications each publish two to three pieces.It should be noted that the "Other" category includes all journals that publish one article apiece, which totals 49 journals and accounts for 56.98% of all journals.In short, the rationale for the dispersion of these journals is tied to the journals' effect and perspective.

Main Authors
This study identified more than 79 authors who have published documents on Scopus.However, 76 authors published only one document which does not make this their main area of expertise.As can be seen in Table 3, only 3 authors published more than 1 article.In terms of productivity, the primary author is Xianchuang Yang, with five publications directly related to the topics analyzed.His research is related to the analysis of sustainable development in green purchase marketing in terms of consumer, social, business and environmental psychology using multiple regression analysis.This research shows that persuasion from the media, climate change through consumer goals, and gender positively impact green buying behavior through perceptions of the seriousness of environmental issues.An interesting finding in this article is that there are differences in personal ecological characteristics between men and women, where task-oriented men must present visual information to highlight the functions of environmentally friendly products, and verbal information for female consumers because women are more sensitive to auditory information.Another interesting fact that Yang wrote about is that his research on green buying behavior is also associated with the COVID-19 phenomenon that shocked the world in 2020-2021.Even more interesting because his research took samples from the people of China, which is the country of origin of COVID-19.The findings show that NEAR to COVID-19 significantly moderates the generation of awareness of Green Purchasing Behavior negatively, as people prefer short-term living solutions and surviving during a pandemic, over doing GPB.
In the second most published, SM Fattah points out that his research explores the level of green skepticism among young consumers, promoting environmental protection must be conveyed with an emotional and gentle message indirectly so that only it can generate a more involved green response from young consumers.Data collection conducted in India shows that maintaining and developing pro-environmental understanding through environmental education (promoting a better mindset towards environmentally friendly and sustainable products) is very important for the economy of a developing country like India.The method used by SM Fattah uses regression, the maximum likelihood method (MLM), and the structural equation model (SEM).Although he is not the author with the most articles, Uddin is the author whose articles are most cited compared to the other two, namely 84 citations.Azila Jaini's work aims to consider eWOM as a new multidimensional construct in the green marketing literature.With 60 citations obtained from two published journals, the authors conducted research with a focus on pharmaceutical and health marketing, particularly in the cosmetic field.Hedonic values have a significant and positive effect on pro-environmental beliefs, while altruistic values have no significant effect on proenvironmental beliefs.

Most Cited Articles
The keywords used in the articles and abstract are the analyzed and create a co-accurance map of all the terms used in 86 articles using Vosviewer software.The year 2018 stands out for the number of citations, reaching its maximum of 341.The most cited article is "Green purchasing behavior: A conceptual framework and empirical investigation of Indian consumers", the authors used structural equation modeling (SEM) to analyzed data from 351 Indian consumers.In the model, Green Purchase Intention (GPI) size was discovered to be a significant predictor of green purchasing behavior (GPB).

Trends in Keywords
Keyword analysis identified from the most widely used and related to the study conducted.This study identified 1,786 different keywords, used a minimum number of occurrences of a term of 5 keywords and produced a number of terms to be selected in 71, then reduced words that were not related to the research objectives.From these results the relevance score is calculated.Title and abstract are used to extract data.To extract the most terms from a publication, ignore the structure abstract labels and ignore the copyright statements.These values led to the identification of 43 items and 4 clusters.
The node size shows the number of repetitions of each keyword, the larger node size will show more often the occurrence of each keyword.The approximate distance between two clusters reveals how closely related they are in terms of citations.Also, the thickness of these lines indicates the intensity of the link, whereas thicker lines appear together more often.The twenty seven items is the most relevant terms in this study is young consumer, perception, purchase, service, effectiveness, environmental consciousness, gpi, green purchase intention, research model, green purchase behaviour, behaviour, individual, green purchase, customer, country, malaysia, green marketer, environmental issue, subjective norm, planned behavior, china, business, green purchasing, green consumption, gender, age, green purchasing behaviour.In this sense, many Chinese and Malaysian Universities have added specialties related to green purchase/purchasing behavior.This study is mainly related to the business, service, environment field.Dimensions of age, gender, customers, effectiveness are some of the things that are often studied.
The Words "green purchase behavior" and "purchasing behavior" are two of the major nodes.The terms "purchase behavior" and "green purchase intention (GPI)" are clustered together and appear relatively close to one another, indicating that these are words that frequently appear together, same with word "green purchasing behaviour" and "green consumption".Additionally, "green purchase behavior" and "green purchasing intention" are next to one another, indicating a close association between the two, but have a long distance with "young consumer".The software groups items by color.Each color is a cluster, and each keyword can only belong to one cluster.Keywords in the same cluster indicate that they are highly related to each other.The clusters found are compiled in table 5.
Cluster #1 being the largest group with 13 items: behaviour, country, customer, gpi, green attitude, green purchase, green purchase attitude, green purchase behaviour, green purchase intention, individual, malaysia, research limitation implication, and research model, they can relate to attitude, implication, and behaviour of customer doing green purchase.Cluster #2 with 11 items can relate to: age, business, china, consumer effectiveness, environmental problem, gender, green consumption, green purchasing, green purchasing behaviour, nature, and policymaker is related to business and their environmental problem with policy applied to.Cluster #3 the blue highlights the terms of measurement of environmental consciousness in a company with 11 items, include: company, effectiveness, environmental attitude, environmental consciousness, green marketing, india, moderating role, perception, purchase, service, young consumer.Finally, cluster #4 with yellow color have behavioral control, environmental issue, green marketer, planned behavior, purchase intention, structural equation, subjective norm, and theory of planned behaviour (tpb) showing us that interest in knowing about theory of planned behaviour.Study about theory of planned behaviour.
Trend analysis is analyzed in figure 2 using a blue to yellow color scale.Blue to yellow colors categorize research that has been done a lot (not innovative) to the newest (most innovative).An analysis of the results reveals that the most productive period, between 2018 and 2022, has produced the newest publication, include structural equation model, china, covid, area, consumption value, smart pls, sustainable development, empirical analysis, significant positive effect, participant, square structural equation mode, epistemic value, functional value, green consumer, green behavior, green skepticism, and social norm.
The term "green purchasing behavior" has been around since 2018 because it uses a dark blue color."Green purchasing behavior" is interesting because it is related to environmental problems because it is connected with the keywords "environmental problem", "environmental awareness" in the first period and the keyword "research limitation imitation" indicating that there are still many limitations to green purchasing research in that period.Then the green color appears as a solution to the "environmental issue", seen from the emergence

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of the keywords "green purchasing", "green consumption", "green marketing".In a more recent period, "moderating role" towards "company", "individual", "gender", and "age" began to be examined.Because sustainability requires a long-term view, which is inherent in the idea of generativity, greater research should be done on the impact of generativity on green purchasing behavior.Additionally, the links between generativity and green purchasing behavior are studied, as well as the "moderating role" of man-nature orientation and perceived "behavioral control".Finally, there is a warm term to measure green purchasing, namely "green attitude", bearing in mind that today's consumer buying behavior is increasingly consumptive and environmental pollution is increasingly being ignored.The country "China" has recently become a country whose universities are intensively conducting research in the field of GPB compared to the country "Malaysia".

Figure 4. Keyword Trend Visualization
Furthermore, in the density visualization, the colors at the nodes that are getting brighter (yellow) represent keywords in journals that have often become a research topic.In our research using Scopus indexed journals, the keyword "green purchase/purchasing behavior" has been widely studied.Meanwhile, darker colored nodes such as "perception" from "age" or "country" to green purchase marking can be the next research opportunity because this topic is still very broad to be researched.204

Trends in Publication
The first journal that contributed to this research was conducted in 2013.This early period of research investigated which factors influence green purchase behavior in the younger generation (Samarasinghe & Samarasinghe, 2013); (Kanchanapibul, 2014); (Dagher & Itani, 2014).In this case, the factors studied include ecological effects, knowledge and perceived seriousness of environmental problems that determine young consumers doing green innovations on their purchase behavior.Interestingly, recent research says that perceived seriousness of environmental problems is still the strongest predictor of green purchasing behavior with respect to environmentally friendly products in developing countries (Suki, 2019) .Problems regarding the environment in the last decade have become a growing concern not only in regulations, but also the general public is increasingly proactive in its role in protecting the environment (Sousa et al., 2022).
The latest research in 2023 is of course research on green purchasing behavior that has a lot to do with COVID-19, such as research conducted (Yang et al., 2023) because this topic is hot for research.Factors that affect people's green purchasing behavior (GPB) are also still a topic of research, but research looks at the influence of the New Environmental Paradigm (NEP) as done by (Yuniasih, 2023).Another study conducted by (Correia et al., 2023), this journal explores the correlation between consumers' attention to companies' green marketing communication and green purchasing behavior, the results show that the higher a person's education level and green attitude and female, the more attentive she is to companies' green marketing communications.This study has added to existing knowledge and understanding of important and recent factors in the adoption of green purchase behavior.This can help to understand which are the most important factors that can help improve GPB for consumers that researchers and companies can take advantage of.

Limitation
This study aims to look at GPB trends in the last ten years, but there has been no discussion of "challenges" in the future GPB in more depth, mapping of "countries'' that have been intensively conducting research on this theme in the last 10 years, as well as what kind of green products consumer demand to generate interest in GPB.This could be an interesting research to be discussed further equipped with more solid arguments.

Conclusions
The results of research that looked at GPB trends in the last 10 years were indexed by Scopus and used the Publish or Perish reference manager and then analyzed the results using Vosviewer.These values led to the identification of 43 items and 4 clusters.Cluster #1 being the largest group with 13 items and they can relate to attitude, implication, and behaviour of customer doing green purchase.Cluster #2 with 11 items can relate to business and their environmental problem with policy applied to.Cluster #3 the blue highlights the terms of measurement of environmental consciousness in a company with 11 items.Finally, cluster #4 with yellow color showing us that interest in knowing about theory of planned behavior.
Green Purchasing Behavior has become a tool to see the novelty of research topics.From this literature study, several conclusions were obtained.First, GPB is a study that has massively expanded in the academic field, especially since 2018, this shows that environmental problems are getting more serious so that regulations related to green marketing are increasingly being strengthened.Second, The Journal of Cleaner Production is an international transdisciplinary publication that focuses on research and application related to Cleaner Production, the environment, and sustainability becoming the most popular source so that research in the fields of tourism and religion is still little done.Third, GPB has been extensively studied in Asian countries, such as China, India, Malaysia, Indonesia and Pakistan, indicating that environmental issues in Asian countries are starting to experience an increase.

Figure 1 .
Figure 1.Application Processed Result of the VOSviewer Application from the Reference Data Used

Figure 2 .
Figure 2. Publications by Topic and Year For example, Journal of Cleaner Production, International Journal of Environmental Research and Public Health, Asian Journal of Business Research, Frontiers in Psychology, Journal of Consumer Behavior, Journal of Islamic Marketing, Management of Environmental Quality: An International Journal, and Social Science Journal are flagship outlet in the field of green purchase marketing.

Figure 5 .
Figure 5. Density Visualization of Green Purchasing Behaviour

Table 1 .
Papers Published per Year

Table 2 .
Table 2 displays journals that have two or more publications.Journals with Twio or More Documents Published

Table 3 .
Authors Published More than One Article

Table 4 .
Most Cited Articles

Table 5 .
Cluster Analysis