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Mixed-dimensional perovskites containing mixtures of organic cations hold great promise to deliver highly stable and efficient solar cells. However, although a plethora of relatively bulky organic cations have been reported for such purposes, a fundamental understanding of the materials’ structure, composition, and phase, along with their correlated effects on the corresponding optoelectronic properties and degradation mechanism remains elusive. Herein, we systematically engineer the structures of bulky organic cations to template low-dimensional perovskites with contrasting inorganic framework dimensionality, connectivity, and coordination deformation. By combining X-ray single-crystal structural analysis with depth-profiling XPS, solid-state NMR, and femtosecond transient absorption, it is revealed that not all low dimensional species work equally well as dopants. Instead, it was found that inorganic architectures with lesser structural distortion tend to yield less disordered energetic and defect landscapes in the resulting mixed-dimensional perovskites, augmented in materials with a longer photoluminescence (PL) lifetime, higher PL quantum yield (up to 11%), improved solar cell performance and enhanced thermal stability (T80 up to 1000 h, unencapsulated). Our study highlights the importance of designing templating organic cations that yield low-dimensional materials with much less structural distortion profiles to be used as additives in stable and efficient perovskite solar cells. Ministry of Education (MOE) National Research Foundation (NRF) Published version The authors would like to acknowledge funding from the Singapore National Research Foundation through the IntraCREATE Collaborative Grant (NRF2018-ITC001-001), Energy Innovation Research Program (NRF2015EWT-EIRP003-004 and Solar CRP: S18-1176-SCRP), and MOE Tier 2 project MOE2019-T2-2-097.

Extending halide perovskites' optoelectronic properties to stimuli-responsive chromism enables switchable optoelectronics, information display, and smart window applications. Here, we demonstrate a band gap tunability (chromism) via crystal structure transformation from three-dimensional FAPbBr3 to a ⟨110⟩ oriented FAn+2PbnBr3n+2 structure using a mono-halide/cation composition (FA/Pb) tuning. Furthermore, we illustrate reversible photochromism in halide perovskite by modulating the intermediate n phase in the FAn+2PbnBr3n+2 structure, enabling greater control of the optical band gap and luminescence of a ⟨110⟩ oriented mono-halide/cation perovskite. Proton transfer reaction-mass spectroscopy carried out to precisely quantify the decomposition product reveals that the organic solvent in the film is a key contributor to the structural transformation and, therefore, the chromism in the ⟨110⟩ structure. These intermediate n phases (2 ≤ n ≤ ∞) stabilize in metastable states in the FAn+2PbnBr3n+2 system, which is accessible via strain or optical or thermal input. The structure reversibility in the ⟨110⟩ perovskite allowed us to demonstrate a class of photochromic sensors capable of self-adaptation to lighting. Ministry of Education (MOE) National Research Foundation (NRF) Accepted version This research was funded by National Research Foundation, Prime Minister’s Office, Singapore, under its Competitive Research Programme (CRP Award No. NRF-CRP14-2014-03) and Ministry of Education, Singapore (MOE2019-T2-2-097).

The power conversion efficiency (PCE) of the state-of-the-art large-area slot-die-coated perovskite solar cells (PSCs) is now over 19%, but issues with their stability persist owing to significant intrinsic point defects and a mass of surface imperfections introduced during the fabrication process. Herein, the utilization of a hydrophobic all-organic salt is reported to modify the top surface of large-area slot-die-coated methylammonium (MA)-free halide perovskite layers. Bearing two molecules, each of which is endowed with anchoring groups capable of exhibiting secondary interactions with the perovskite surfaces, the organic salt acts as a molecular lock by effectively binding to both anion and cation vacancies, substantially enhancing the materials’ intrinsic stability against different stimuli. It not only reduces the ingression of external species such as oxygen and moisture, but also suppresses the egress of volatile organic components during the thermal stability testing. The treated PSCs demonstrate efficiency of 19.28% (active area of 58.5 cm2) and 17.62% (aperture area of 64 cm2) for the corresponding mini-module. More importantly, unencapsulated slot-die-coated mini-modules incorporating the all-organic surface modifier show ≈80% efficiency retention after 7500 h (313 days) of storage under 30% relative humidity (RH). They also remarkably retain more than 90% of the initial efficiency for over 850 h while being measured continuously. Ministry of Education (MOE) Nanyang Technological University National Research Foundation (NRF) Submitted/Accepted version The authors would like to acknowledge funding from the Singapore National Research Foundation through the Intra-CREATE Collaborative Grant (NRF2018-ITC001-001), Competitive Research Program (CRP) (NRFCRP25-2020-0002), NRF Investigatorship (NRF-NRFI-2018-04), MOE Tier 2 project MOE2019-T2-2-097, and the Science and Technology Development Fund, Macao SAR (File no. 0082/2021/A2).

The reaction of the bis(thiophosphinoyl) geminal dianion [C(PPh2S)2]2- with B2Br4(SMe2)2 in toluene afforded the diboron-carbene complex [(SPh2P)2CB]2 (2). The lability of the boron-carbene bond was found in the reaction of the sterically hindered thiophosphinoyl iminophosphoranyl geminal dianion [C(PPh2NAr)(PPh2S)]2- (Ar = 2,6-iPr2C6H3) with B2Br4(SMe2)2 in toluene to form the diboron-carbene complex 4, where one boron center bonds with two methanediides, leading to an allyl anionic-like C═B←C2- electronic structure, while another boron center is stabilized by two imino substituents. Complex 4 underwent rearrangement via a 1,2-methanediide shift in toluene at 60 °C to give the diboron-carbene complex [(SPh2P)(ArNPh2P)CB]2 (5). Ministry of Education (MOE) This work was supported by the Ministry of Education Singapore, AcRF Tier 1 (RG121/17) (C.-W.S.). M.-C.Y. and M.-D.S. are grateful to the Ministry of Science and Technology of Taiwan for financial support.

This investigation has characterised the structure and surface chemistry of CsPbBr3 nanocrystals with controlled diameters between 6.4 to 12.8 nm. The nanocrystals were investigated via a thorough 133Cs solid state NMR and nuclear relaxation study, identifying and mapping radially-increasing nanoscale disorder. This work has formalised 133Cs NMR as a highly sensitive probe of nanocrystal size, which can conveniently analyse nanocrystals in solid forms, as they would be utilised in optoelectronic devices. A combined multinuclear solid state NMR and XPS approach, including 133Cs–1H heteronuclear correlation 2D (HETCOR) NMR, was utilised to study the nanocrystal surface and ligands, demonstrating that the surface is Cs–Br rich with vacancies passivated by didodecyldimethylammonium bromide (DDAB) ligands. Furthermore, it is shown that a negligible amount of phosphonate ligands remain on the powder nanocrystal surface, despite the key role of octylphosphonic acid (OPA) in controlling the colloidal nanocrystal growth. The CsPbBr3 NCs were shown to be structurally stable under ambient conditions for up to 6 months, albeit with some particle agglomeration.

Metal lead halide perovskite nanocrystals have emerged as promising candidates for optoelectronic applications. However, the inclusion of toxic lead is a major concern for the commercial viability of these materials. Herein, we introduce a new family of non-toxic reduced dimension Rb2CuX3 (X= Br, Cl) colloidal nanocrystals with one-dimensional crystal structure consisting [CuX4]3- ribbons isolated by Rb+ cations. These nanocrystals were synthesised using a room-temperature method under ambient conditions, which makes them cost effective and scalable. Phase purity quantification was confirmed by Rietveld refinement of powder x-ray diffraction and corroborated by 87Rb MAS NMR technique. Both samples also exhibited high thermal stability up to 500°C, which is essential for optoelectronic applications. Rb2CuBr3 and Rb2CuCl3 displays PL emission peaks at 387 nm and 400 nm with high PLQYs of ~100% and ~49%, respectively. Lastly, the first colloidal synthesis of quantum-confined rubidium copper halide-based nanocrystals opens up a new avenue to exploit their optical properties in lighting technology as well as water sterilisation and air purification. National Research Foundation (NRF) P.V. acknowledges a Presidential Postdoctoral Fellowship from Nanyang Technological University (NTU), Singapore via grant 04INS000581C150OOE01. M.K., N.M., S.G.M., and T.W. acknowledge financial support from the Singapore National Research Foundation, Prime Minister's Office, through the Competitive Research Program (CRP Award No. NRF-CRP14-2014-03). T.C.S and D.G. acknowledge the financial support from the NRF Investigatorship (NRF-NRFI-2018-04) and the Ministry of Education under its AcRF Tier 1 grant (RG91/19) and Tier 2 grant MOE2019-T2-1-006. The authors would like to acknowledge the Facility for Analysis, Characterization, Testing and Simulation (FACTS) at NTU, Singapore, for use of their electron microscopy and X-ray diffraction facilities. We would also like to acknowledge the NTU Centre of High Field NMR Spectroscopy and Imaging for the use of their NMR facilities. We thank Mr. Sai S. H. Dintakurti and Dr. Ankit, NTU, Singapore.

Inorganic cesium lead halide perovskite nanocrystals are promising materials for optoelectronic applications as they exhibit high thermal stability alongside precise color tunability and high color purity; however, their optical properties are degraded by surface defects. This work demonstrates a room temperature synthesis of CsPbBr3 nanocrystals facilitating in situ surface passivation via the incorporation of Zn2+ cations. The facile incorporation ZnBr2 into the precursor solution facilitates Zn2+ and Br− substitution into the nanocrystal surface/subsurface layers to induce passivation of existing Pb2+ and Br– vacancies and increase the photoluminescence quantum yield from ∼48 to 86%. The XPS and solid-state 1H MAS NMR techniques show that the key modification is a reduction of the octylamine:oleic acid ratio leading to a near-neutral surface charge; this is accompanied by the appearance of larger nanosheets and nanowires observed by quantitative powder XRD and HR-TEM. The suitability of these perovskite nanocrystals for electrically driven applications was confirmed by the fabrication of light-emitting diodes, which demonstrate that the in situ Zn2+ passivation strategy enhanced the external quantum efficiency by ∼60%. National Research Foundation (NRF) PV acknowledges a Presidential Postdoctoral Fellowship from Nanyang Technological University (NTU), Singapore via grant 04INS000581C150OOE01. We acknowledge financial support from the Singapore National Research Foundation, Prime Minister’s Office, through the Competitive Research Program (CRP Award No. NRF-CRP14-2014-03). The authors would like to acknowledge the Facility for Analysis, Characterization, Testing and Simulation (FACTS) at NTU, Singapore, for use of their electron microscopy and X-ray diffraction facilities. We would also like to acknowledge the NTU Center of High Field NMR Spectroscopy and Imaging for the use of their NMR facilities. The authors would also like to thank Prof. Nripan Mathews and Dr. Nur Fadilah Jamaludin for the valuable discussion, Mr. Sai S. H. Dintakurti for discussions with aspects of the crystallographic analysis and Mr. Gautam V. Nutan for assistance with the XPS measurements. JVH acknowledges financial support for the solid state NMR instrumentation at Warwick used in this research which was funded by EPSRC (grants EP/M028186/1 and EP/K024418/1), the University of Warwick, and the Birmingham Science City AM1 and AM2 projects which were supported by Advantage West Midlands (AWM) and the European Regional Development Fund (ERDF). AAMB acknowledges the Tizard studentship from the Faculty of Engineering and Physical Sciences at University of Southampton.

The spin coating method was employed to fabricate Yb-doped ZnO thin films at 0, 3, 5, 7, and 9 at.% over a glass substrate at low temperature. X-ray diffraction analysis revealed that the hexagonal wurtzite structure was retained even at high doping contents. With the incorporation of Yb+3 ions, a slight decrease in the lattice parameters and crystallite size was observed as the ytterbium content increased. X-ray photoelectron spectroscopy confirmed the presence of ytterbium in the doped ZnO films, and the oxidation state of ytterbium was 3+ for all the samples. Morphological studies revealed a surface microstructure formed by micro islands, which tended to be denser as the ytterbium content increased. Optical transmittance was observed at approximately 75–85%, a blueshift was observed, and consequently, an increase in the bandgap, which varies from 3.0 to 3.2 eV, was observed. The refractive index and extinction coefficient decreased as the ytterbium dopant concentration increased. The photoluminescence results exhibited a strong ultraviolet emission, allowing the use of these thin films in optoelectronic applications.

Metal halide perovskites have shown excellent properties for lighting applications, including high photoluminescence quantum yield (PLQY), compositional tunability, and narrow emission line widths....

Typical fabrication methods for laboratory-scale (

This investigation has characterised the structure and surface chemistry of CsPbBr

Major strides have been made in the development of materials and devices based around low-dimensional hybrid group 14 metal halide perovskites. Thus far, this work has mostly focused on compounds containing highly toxic Pb, with the analogous less toxic Sn materials being comparatively poorly evolved. In response, the study herein aims to (i) provide insight into the impact of templating cations upon the structure of

Room-temperature perovskite nanocrystal syntheses have previously lacked the size tunability attainable through high-temperature methods. Herein, we outline a scalable approach whereby the nucleation and growth of CsPbBr3 nanocrystals (NCs) can be decoupled and controlled at room temperature by utilizing different ligands. We employed octylphosphonic acid (OPA) ligands to regulate the critical radius and the NC growth rate. The subsequent addition of a bulkier didodecyldimethylammonium bromide ligand quenches the NC growth, defining the reaction duration. Management of these three variables enables precise tuning of the NC diameter between 6.8 and 13.6 nm. The photoluminescence quantum yield of the NCs remains above 80% for all sizes even after thorough antisolvent purification. The use of hydrogen-bonding OPA ligands enhances quantum confinement effects, characterized by strong, well-resolved absorption peaks. Solution and solid-state nuclear magnetic resonance spectra confirmed the effective removal of unbound ligands during purification and the presence of a hydrogen-bonded network of OPA ligands on the surface of the purified NCs. Overall, this approach has the potential to facilitate a broad range of future endeavors from studies of hot carrier dynamics to both optically and electrically driven device applications. Accepted version

When exposed to carbonation, Na2CO3-activated slag (SCAS) concrete demonstrated 53% mass loss and 57% reduction in compressive strength due to the decalcification of C-(A)-S-H. Improvements in the carbonation resistance of SCAS mixes via the inclusion of hydromagnesite seeds (S) and reactive MgO (M) were reported in this study. The conversion of MgO into hydrated magnesium carbonates (HMCs) and the additional formation of hydrotalcite were observed in the presence of these additives. HMCs contributed to the binding network and limited the diffusion of CO2 into the sample. The decalcification of C-(A)-S-H was retarded via the absorption of CO2 in hydrotalcite, producing huntite. These changes in the reaction kinetics of samples involving M and S enabled the retention of hydration products and formation of additional carbonation products, leading to denser microstructures and ~40% increase in compressive strength after carbonation, which was ~10 times higher than the control sample (58 vs. 6 MPa).

This investigation has characterised the structure and surface chemistry of CsPbBr3 nanocrystals with controlled diameters between 6.4 to 12.8 nm. The nanocrystals were investigated via a thorough 133Cs solid state NMR and nuclear relaxation study, identifying and mapping radially-increasing nanoscale disorder. This work has formalised 133Cs NMR as a highly sensitive probe of nanocrystal size, which can conveniently analyse nanocrystals in solid forms, as they would be utilised in optoelectronic devices. A combined multinuclear solid state NMR and XPS approach, including 133Cs-1H heteronuclear correlation 2D (HETCOR) NMR, was utilised to study the nanocrystal surface and ligands, demonstrating that the surface is Cs-Br rich with vacancies passivated by didodecyldimethylammonium bromide (DDAB) ligands. Furthermore, it is shown that a negligible amount of phosphonate ligands remain on the powder nanocrystal surface, despite the key role of octylphosphonic acid (OPA) in controlling the colloidal nanocrystal growth. The CsPbBr3 NCs were shown to be structurally stable under ambient conditions for up to 6 months, albeit with some particle agglomeration. Ministry of Education (MOE) National Research Foundation (NRF) Submitted/Accepted version We thank the Singapore Ministry of Education, under the grant MOE2019-T2-2-032, and the Singapore National Research Foundation, under its Competitive Research Program (CRP Award No. NRF-CRP14-2014-03), for funding this research. A. A. M. B. gratefully acknowledges the Tizard studentship from the Faculty of Engineering and Physical Sciences at the University of Southampton.

Heterostructures, combining perovskite nanocrystals (PNC) and chalcogenide quantum dots, could pave a path to optoelectronic device applications by enabling absorption in the near-infrared region, tailorable electronic properties, and stable crystal structures. Ideally, the heterostructure host material requires a similar lattice constant as the guest which is also constrained by the synthesis protocol and materials selectivity. Herein, we present an efficient one-pot hot-injection method to synthesize colloidal all-inorganic cesium lead halide-lead sulfide (CsPbX3 (X = Cl, Br, I)-PbS) heterostructure nanocrystals (HNCs) via the epitaxial growth of the perovskite onto the presynthesized PbS nanocrystals (NCs). Optical and structural characterization evidenced the formation of heterostructures. The embedding of PbS NCs into CsPbX3 perovskite allows the tuning of the absorption and emission from 400 to 1100 nm by tuning the size and composition of perovskite HNCs. The CsPbI3-PbS HNCs show enhanced stability in ambient conditions. The stability, tunable optical properties, and variable band alignments accessible in this system would have implications in the design of novel optoelectronic applications such as light-emitting diodes, photodetectors, photocatalysis, and photovoltaics. Ministry of Education (MOE) Nanyang Technological University National Research Foundation (NRF) Accepted version M.J. acknowledges the National Research Foundation, Prime Minister’s Office, Singapore, under its Competitive Research Programme (CRP Award NRF-CRP14-2014-03). We acknowledge the Facility for Analysis, Characterization, Testing and Simulation, Nanyang Technological University, Singapore, for use of their electron microscopy/X-ray facilities. M.J. acknowledge National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. 2020R1A4A1019455). P.V. acknowledges a Presidential Postdoctoral Fellowship from Nanyang Technological University (NTU), Singapore, via Grant 04INS000581C150. We also acknowledge the NTU Centre of High Field NMR Spectroscopy and Imaging for the use of their NMR facilities. T.C.S. and J.W.M.L. acknowledge the financial support from the Singapore National Research Foundation through the NRF Investigatorship (NRF-NRFI-2018-04) and the Ministry of Education under its AcRF Tier 1 Grant RG91/19 and Tier 2 Grant MOE2019-T2-1-006.

Major strides have been made in the development of materials and devices based around low-dimensional hybrid group 14 metal halide perovskites. Thus far, this work has mostly focused on compounds containing highly toxic Pb, with the analogous less toxic Sn materials being comparatively poorly evolved. In response, the study herein aims to (i) provide insight into the impact of templating cations upon the structure of n = 1 2D tin iodide perovskites (where n refers to the number of contiguous two-dimensional (2D) inorganic layers, i.e., not separated by organic cations) and (ii) examine their potential as light absorbers for photovoltaic (PV) cells. It was discovered through systematic tuning of organic dications that imidazolium rings are able to induce the formation of (110)-oriented materials, including examples of "3 × 3" corrugated Sn-I perovskites. This structural outcome is a consequence of a combination of supramolecular interactions of the two endocyclic N atoms of the imidazolium rings with the Sn-I framework, and the comparatively high tendency of Sn2+ ions to stereochemically express their 5s2 lone pairs . More importantly, the resulting materials feature very short separations between their 2D inorganic layers with iodide-iodide (I···I) contacts as small as 4.174 Å, which is among the shortest ever recorded for 2D tin iodide perovskites. These proximate inorganic distances, combined with the polarizable nature of the imidazolium moiety, eases the separation of photogenerated charge within the materials. This is evident from the measurement of excitonic activation energies as low as 83(10) meV for ImEA[SnI4]. When combined with superior light absorption capabilities relative to their lead congeners, this allowed the fabrication of lead-free solar cells with incident photon-to-current and power conversion efficiencies of up to 70% and 2.26%, respectively, which are among the highest values reported for pure n = 1 2D group 14 metal halide perovskites. In fact, these values are superior to the corresponding lead iodide material, which demonstrates that 2D Sn-based materials have significant potential as less toxic alternatives to their Pb counterparts. Ministry of Education (MOE) Nanyang Technological University National Research Foundation (NRF) J.E.is grateful to NTU for funding (M4081442). S.G. M., N.M., B.F., T. M.K., and T.J.N.H. would like to acknowledge funding from the Singapore National Research Foundation through the IntraCREATE Collaborative Program (NRF2018-ITC001-001), Office of Naval Research Global (ONRG-NICOP-N62909-17-1-2155), and the Competitive Research Program: NRF-CRP14-2014-03. Y.L. and Z.X.S. would like to acknowledge Ministry of Education of Singapore for the funding through AcRF Tier 1 (ref RG195/17 and RG156/19).

Realization of reduced ionic (cationic and anionic) defects at the surface and grain boundaries (GBs) of perovskite films is vital to boost the power conversion efficiency of organic-inorganic halide perovskite (OIHP) solar cells. Although numerous strategies have been developed, effective passivation still remains a great challenge due to the complexity and diversity of these defects. Herein, a solid-state interdiffusion process using multi-cation hybrid halide perovskite quantum dots (QDs) is introduced as a strategy to heal the ionic defects at the surface and GBs. It is found that the solid-state interdiffusion process leads to a reduction in OIHP shallow defects. In addition, Cs+ distribution in QDs greatly influences the effectiveness of ionic defect passivation with significant enhancement to all photovoltaic performance characteristics observed on treating the solar cells with Cs0.05 (MA0.17 FA0.83 )0.95 PbBr3 (abbreviated as QDs-Cs5). This enables power conversion efficiency (PCE) exceeding 21% to be achieved with more than 90% of its initial PCE retained on exposure to continuous illumination of more than 550 h. Nanyang Technological University National Research Foundation (NRF) N.M., S.G.M. would like to acknowledge funding from the Singapore National Research Foundation through the Intra-CREATE Collaborative Grant (NRF2018-ITC001-001). P.V. acknowledges Presidential Postdoctoral Fellowship visa grant M408070000.

Halide perovskites are of great interest for light-emitting diodes (PeLEDs) in recent years due to their excellent photo- and electroluminescence properties. However, trap/defects and ion migration of devices under high external driving voltage/current are yet overcome. In this work, it is found that upon potassium (K) addition to a CsPbBr3/Cs4PbBr6 (3D:0D = 0.85:0.15) perovskite, a locally-disordered 0D Cs4-xKxPbBr6 phase is formed with nearly 0.35:0.65 admixture of 0D:3D, along with an unreacted KBr phase potentially passivating the surface and grain boundaries. The formation of CsPbBr3 nanocrystals (~10nm) confined within the Cs4-xKxPbBr6 matrix accompanied by larger CsPbBr3 grains (~50nm) is further confirmed by high-resolution transmission electron microscopy. In addition, the kinetics of ion migration were characterized with Auger electron spectroscopy and double-layer polarization using capacitive-frequency measurements, revealing significantly lower hysteresis, halide ion migration and accumulation for the K-incorporated samples during device operation, resulting in substantial improvements in LED performances and stability. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Accepted version

The ability to clearly relate local structure to function is desirable for many catalytically relevant Pd-containing systems. This report represents the first direct 105Pd solid state NMR measurements of diamagnetic inorganic (K2Pd(IV)Cl6, (NH4)2Pd(IV)Cl6 and K2Pd(IV)Br6) complexes, and micron- and nano-sized Pd metal particles at room temperature, thereby introducing effective 105Pd chemical shift and Knight shift ranges in the solid state. The very large 105Pd quadrupole moment (Q) makes the quadrupole parameters (CQ, ηQ) extremely sensitive to small structural distortions. Despite the well-defined high symmetry octahedral positions describing the immediate Pd coordination environment, 105Pd NMR measurements can detect longer range disorder and anisotropic motion in the interstitial positions. The approach adopted here combines high resolution X-ray pair distribution function (PDF) analyses with 105Pd, 39K and 35Cl MAS NMR, and shows solid state NMR to be a very sensitive probe of short range structural perturbations. Solid state 105Pd NMR observations of ∼44–149 μm Pd sponge, ∼20–150 nm Pd black nanoparticles, highly monodisperse 16 ± 3 nm PVP-stabilised Pd nanoparticles, and highly polydisperse ∼2–1100 nm biomineralized Pd nanoparticles (bio-Pd) on pyrolysed amorphous carbon detect physical differences between these systems based on relative bulk:surface ratios and monodispersity/size homogeneity. This introduces the possibility of utilizing solid state NMR to help elucidate the structure–function properties of commercial Pd-based catalyst systems.\ud \ud

Al-rich aluminum borates were prepared by different synthesis routes using various Al/B ratios, characterized by diffraction methods, spectroscopy and prompt gamma activation analysis. The 11B NMR data show a small amount of BO4 species in all samples. The chemical analysis indicates a trend in the Al/B ratio instead of a fixed composition. Both methods indicate a solid solution Al5−xB1+xO9 where Al is substituted by B in the range of 1–3%. The structure of B-rich Al4B2O9 (C2/m, a=1488 pm, b=553 pm, c=1502 pm, s=90.6°), was re-investigated by electron diffraction methods, showing that structural details vary within a crystallite. In most of the domains the atoms are orderly distributed, showing no signal for the postulated channel oxygen atom O5. The absence of O5 is supported by density functional theory calculations. Other domains show a probable disordered configuration of O5 and O10, indicated by diffuse scattering along the b direction.

It is well-established that the inclusion of small atomic species such as boron (B) in powder metal catalysts can subtly modify catalytic properties, and the associated changes in the metal lattice imply that the B atoms are located in the interstitial sites. However, there is no compelling evidence for the occurrence of interstitial B atoms, and there is a concomitant lack of detailed structural information describing the nature of this occupancy and its effects on the metal host. In this work, we use an innovative combination of high-resolution 11B magic-angle-spinning (MAS) and 105Pd static solid-state NMR nuclear magnetic resonance (NMR), synchrotron X-ray diffraction (SXRD), in situ X-ray pair distribution function (XPDF), scanning transmission electron microscopy-annular dark field imaging (STEM-ADF), electron ptychography, and electron energy loss spectroscopy (EELS) to investigate the B atom positions, properties, and structural modifications to the palladium lattice of an industrial type interstitial boron doped palladium nanoparticle catalyst system (Pd-intB/C NPs). In this study, we report that upon B incorporation into the Pd lattice, the overall face centered cubic (FCC) lattice is maintained; however, short-range disorder is introduced. The 105Pd static solid-state NMR illustrates how different types (and levels) of structural strain and disorder are introduced in the nanoparticle history. These structural distortions can lead to the appearance of small amounts of local hexagonal close packed (HCP) structured material in localized regions. The short-range lattice tailoring of the Pd framework to accommodate interstitial B dopants in the octahedral sites of the distorted FCC structure can be imaged by electron ptychography. This study describes new toolsets that enable the characterization of industrial metal nanocatalysts across length scales from macro- to microanalysis, which gives important guidance to the structure-activity relationship of the system.