Near-infrared spectroscopy is an important analytical method, widely used in materials science, biological science, and optical research. This paper comprehensively reviews the basic knowledge, principles of near-infrared spectroscopy, and its application in the trace identification of sulfur poisoning at the nanoscale. What is near-field infrared spectroscopy? Near-infrared spectroscopy (NIRS) is an investigative process that uses a generator emitting light with a specified frequency and wavelength spectrum (usually 800-2500nm), enabling researchers to obtain a comprehensive image of the organic components of the substance under investigation. It utilizes the near-infrared region of the electromagnetic spectrum. Over the past two decades, near-infrared spectroscopy has made significant progress in many fields such as equipment, spectral analysis, and implementation, and has been widely used as a powerful tool in various industries. A brief history of near-field infrared spectroscopy Although NIR spectroscopy is considered a relatively recent technology, its origins can be traced back to 1800, when it was determined that electromagnetic radiation scattering beyond the visible part of the spectrum could be observed using a series of thermometers with dimmed light bulbs. However, major advancements occurred around the 1960s, allowing its implementation in many areas of animal husbandry and other sectors. The working principle of near-field infrared spectroscopy The broad fringes in NIR spectroscopy are caused by strong absorption at adjacent frequencies. Near-infrared spectral absorption bands are mainly a mixture of harmonics and phonon modes with various chemical bonds. The ionization waves absorbed from such chemical bonds at NIR wavelengths provide a spectrum characteristic of the material, acting as a "fingerprint". The collected spectrum contains information about the physical and chemical properties of the natural components in the sample, as well as basic information about the chemical composition. What materials are used in catalytic processes? Catalysis is an essential process and a pillar of multiple industries. Improving catalyst lifespan and durability is a major area of cross-disciplinary analysis. Many catalytic processes involve the use of platinum group metal (PGM) nanoparticles (NPs) and multimetallic structures with different sizes, morphologies, and topologies, which are dispersed on permeable metal oxide support substrates. Sulfur-containing compounds, such as SOx, can attach firmly and often permanently to platinum group metals as well as metal oxide support substrates, ultimately leading to catalytic deactivation and reducing catalytic conversion and specificity. Sulfur poisoning - a serious threat to catalytic processes Catalytic deactivation caused by sulfur toxicity is a key challenge in various industrial chemical methods. This includes complex processes such as solid oxide fuel cells (SOFCs), catalytic exhaust gas emission control frameworks, industrial (improved) Claus processes, catalytic hydrocarbon pyrolysis structures, photo/electrocatalytic water electrolysis, and large-scale sulfuric acid production. Challenges in sulfur poisoning research The scientific knowledge at the molecular level to fully understand and eradicate this significant problem remains incomplete. This is because a comprehensive understanding of sulfur poisoning requires advanced experimental methods to achieve nanoscale positional accuracy without affecting the details of chemical bonds, adsorption sites, and adsorption morphologies. Limitations of traditional spectroscopic methods Unfortunately, most traditional spectroscopic, microscopic, and crystallographic methods used to characterize reactive metal/metal-oxide interfaces suffer from a trade-off between high resolution and chemical structure/bonding specificity. Scanning tunneling/atomic force/transmission electron microscopy (STM/AFM/TEM) typically cannot simultaneously provide relevant information about biochemical organic compounds, structural properties, and the adsorption morphology of catalytic adsorption sites. For collecting comprehensive data, these methods are usually limited to impractically low concentrations (10-12 atm) and cryogenic conditions (below 20 K). Some of these procedures may also cause sample damage due to the use of high-energy electrons or radiation. Advantages of NFIR over traditional technologies Infrared (IR) photons used in far-field optical spectroscopy/microscopy can provide comprehensive chemical/bonding/adsorption morphology data without causing sample degradation. However, due to the diffraction limit, they are restricted to a potential pixel size of >1.2 μm. Therefore, typical far-field infrared spectroscopy/microscopy studies of metal/metal-oxide catalytic integration yield complex results from many regions, making uniquely accurate identification of specific adsorbates in individual areas impossible. Latest research Ozensoy et al. published an article in the Journal of the American Chemical Society, demonstrating the use of scanning NFIR to identify and analyze sulfur poisoning. The resulting data showed that due to differences in surface morphology, the types of adsorbents on the surface and their adsorption modes on the catalyst surface may vary significantly not only on specific PGM nanoparticles but also among several PGM nanoparticles. The near-field signal intensity varies with tip-surface contact, peak interface proximity, tip/disk configuration, and near-field connections between nearby disks. Recent DFT theoretical results indicate that changing the toxic amount of sulfate by varying the H2SO4 (aq) contact time can alter not only the adsorption mode but also the adsorption strength of sulfate on Pd nanodisks/Al2O3 (thin film)/Si (100) surfaces. Catalysis has always been an important industrial driver, with an international economic value of up to 34 billion US dollars by 2025, at an annual growth rate of 4.5%. Research is needed to further understand the chemical nature of sulfur poisoning to avoid this phenomenon.