The Tauc plot is a method originally developed to derive the optical gap of amorphous semiconductors such as amorphous germanium or silicon. By measuring the absorption coefficient α(hν) and plotting versus photon energy hν, a value for the optical gap (Tauc gap) is determined. In this way non‐direct optical transitions between approximately parabolic bands can be examined. In the last decades, a modification of this method for (poly‐) crystalline semiconductors has become popular to study direct and indirect interband transitions. For this purpose, (ahν)ⁿ (n = , 2) is plotted against hν to determine a value of the electronic bandgap. Due to the ease of performing UV–vis measurements, this method has nowadays become a standard to analyze various (poly‐) crystalline solids, regardless of their different electronic structure. Although this leads partially to widely varying values of the respective bandgap of nominally identical materials, there is still no study that critically questions which peculiarities in the electronic structure prevent a use of the Tauc plot for (poly‐) crystalline solids and to which material classes this applies. This study aims to close this gap by discussing the Tauc plot and its limiting factors for exemplary (poly‐) crystalline solids with different electronic structures.

Engineering of defects in semiconductors provides an effective protocol for improving photocatalytic N₂conversion efficiency. This review focuses on the state-of-the-art progress in defect engineering of photocatalysts for the N₂reduction toward ammonia. The basic principles and mechanisms of thermal catalyzed and photon-induced N₂reduction are first concisely recapped, including relevant properties of the N₂molecule, reaction pathways, and NH₃quantification methods. Subsequently, defect classification, synthesis strategies, and identification techniques are compendiously summarized. Advances ofin situcharacterization techniques for monitoring defect state during the N₂reduction process are also described. Especially, various surface defect strategies and their critical roles in improving the N₂photoreduction performance are highlighted, including surface vacancies (i.e., anionic vacancies and cationic vacancies), heteroatom doping (i.e., metal element doping and nonmetal element doping), and atomically defined surface sites. Finally, future opportunities and challenges as well as perspectives on further development of defect-engineered photocatalysts for the nitrogen reduction to ammonia are presented. It is expected that this review can provide a profound guidance for more specialized design of defect-engineered catalysts with high activity and stability for nitrogen photochemical fixation.

Constructing hierarchical and ultrathin‐structured metal sulfides is beneficial for achieving high‐efficiency hydrogen evolution catalysts. Herein, ZnIn₂S₄ (ZIS) hollow nanoflowers (HNFs) composed of ultrathin nanosheets are creatively synthesized via a facile trisodium citrate‐mediated and stirring‐assisted solvothermal method. Experimental results reveal that the synergy effect of ethanol, trisodium citrate, and continuous stirring during solvothermal synthesis process play a significant role in optimizing microstructure as well as physicochemical properties of as‐prepared ZIS samples. Importantly, the fabricated ZIS HNFs with the thinnest nanosheets (2.28 nm) manifest the highest average photocatalytic hydrogen generation rate of 301.5 μmol h⁻¹, which is 2.3 times higher than that of the pristine ZIS microspheres composed of nanoparticles with Pt as the cocatalyst and triethanolamine (TEOA) as the sacrificial agent and outperforms most reported ZnIn2S4‐based materials under similar testing conditions. Moreover, the optimized sample also shows a hydrogen generation rate of 0.53 μmol h^−1.in pure water without any cocatalyst. This controllable agitation of the reaction mixture during the hydro/solvothermal synthesis process offers an eco‐friendly and scalable approach for tuning the microstructure of nanomaterials with enhanced performance for various applications.

Due to significant advances in instrumentation, many previously specialized techniques have become “routine” in user facilities. However, detailed knowledge held by experts has often not been relayed to general users, so they often rely on entry-level information, basic principles, and comparison with literature results for data analysis. As a result, major errors in the data analysis of multiple surface and material analysis techniques, including in x-ray photoelectron spectroscopy (XPS), have been appearing in the scientific literature. Representative examples of serious errors in XPS data analysis are shown in this work. We suggest that surface and material analysis, and perhaps even science in general, are in a state of “pre-crisis.” We use two (logistic) models from population biology to suggest that bad analyses self-correct if they remain below a critical number. However, beyond a threshold, the literature can become useless because of the perpetuation of faulty analyses and concomitant loss of its self-correcting ability. XPS is used by scientists in many communities because of the power of the technique and high-quality instrumentation that is commercially available. Those who make new surfaces and materials face unique challenges because of the large number of surface and material analytical techniques that are often needed to characterize their materials. Graduate students and post-docs are often provided with only minimal instruction on using surface and material characterization methods. High fees for instruments may affect both the quality and the quantity of the data people collect. The Prisoner's Dilemma is a model from game theory that describes situations with reward structures that encourage uncooperative behavior and lead to suboptimal outcomes. However, the outcomes of Prisoner's Dilemma are not inevitable—their consequences change if their reward structures change. The current system does not appear to incentivize detailed learning of surface and material characterization techniques and careful material characterization. Prisoner's dilemmas appear to lead to other undesirable consequences in science. The concerns raised in this work suggest that many manuscripts are incompletely reviewed at present. The different stakeholders in this problem, including authors, research advisers, subject matter experts, reviewers, scientists who notice examples of faulty data analysis, editors, journals and publishers, funding agencies, scientific societies, leaders at universities and research centers, and instrument vendors, can improve the current situation. This work provides specific recommendations for each of these stakeholders. For example, we believe that authors are primarily responsible for the correctness of their work, not reviewers or editors; we question the wisdom of listing the names of the editor and reviewers on a paper; we are grateful for the significant contributions that have been made by subject matter experts to produce standards and tutorial information; the high cost of instrument time at some institutions may limit student access and result in suboptimal analyses; staff scientists often need to be better recognized for their intellectual contributions to studies; publishers may wish to allow selective reviewing of specific sections of papers related to material characterization; the reviewing at some open access journals may be inadequate; while it had its shortcomings, the pre-open access model of publishing incentivized the production and publication of high-quality work; audits of the products (scientific papers) of funding agencies may be necessary; collaboration needs to be encouraged to a greater extent at some institutions; and instrument vendors should not suggest to potential customers that surface characterization, e.g., by XPS, is trivial or simple.