Yung-Kang Peng - Academia.edu (original) (raw)

Papers by Yung-Kang Peng

Chem. Commun., 2016

Near quantitative carbon yields of diesel-range alkanes were achieved from the hydrodeoxygenation... more Near quantitative carbon yields of diesel-range alkanes were achieved from the hydrodeoxygenation of triglycerides over Pd/NbOPO4 under mild conditions with no catalyst deactivation: catalyst characterization and theoretical calculations suggest that the high hydrodeoxygenation activity originated from the synergistic effect of Pd and strong Lewis acidity on the unique structure of NbOPO4.

Journal of Catalysis, 2016

Small, 2014

The room-temperature, aqueous-phase synthesis of iron-oxide nanoparticles (IO NPs) with glutathio... more The room-temperature, aqueous-phase synthesis of iron-oxide nanoparticles (IO NPs) with glutathione (GSH) is reported. The simple, one-step reduction involves GSH as a capping agent and tetrakis(hydroxymethyl)phosphonium chloride (THPC) as the reducing agent; GSH is an anti-oxidant that is abundant in the human body while THPC is commonly used in the synthesis of noble-metal clusters. Due to their low magnetization and good water-dispersibility, the resulting GSH-IO NPs, which are 3.72 ± 0.12 nm in diameter, exhibit a low r2 relaxivity (8.28 mm(-1) s(-1)) and r2/r1 ratio (2.28)--both of which are critical for T1 contrast agents. This, together with the excellent biocompatibility, makes these NPs an ideal candidate to be a T1 contrast agent. Its capability in cellular imaging is illustrated by the high signal intensity in the T1-weighted magnetic resonance imaging (MRI) of treated HeLa cells. Surprisingly, the GSH-IO NPs escape ingestion by the hepatic reticuloendothelial system, enabling strong vascular enhancement at the internal carotid artery and superior sagittal sinus, where detection of the thrombus is critical for diagnosing a stroke. Moreover, serial T1- and T2-weighted time-dependent MR images are resolved for a rat's kidneys, unveiling detailed cortical-medullary anatomy and renal physiological functions. The newly developed GSH-IO NPs thus open a new dimension in efforts towards high-performance, long-circulating MRI contrast agents that have biotargeting potential.

Materials Express, 2011

ABSTRACT We report the development of multi-functional uniform nanoparticles comprising a hollow ... more ABSTRACT We report the development of multi-functional uniform nanoparticles comprising a hollow manganese oxide core and a functionalized mesoporous silica shell (H–MnO@mSiO2 (Ir)@–FA, Ir: an emissive iridium complex, FA: folic acid) for use as theranostic nanocomposites that combine four-in-one functionality, i.e., dual imaging (both magnetic resonance and optical), specific targeting and therapy in a single unit. The H–MnO@mSiO2 (Ir)–FA nanoparticles (NPs) demonstrate its versatility in various applications. (1) The magnetic core provides the capability for T 1magnetic resonance imaging. (2) Phosphorescent iridium complex serves as both photosensitizer and the luminescent chromophore. (3) The nano-channels in the mesoporous silica shell increase the free diffusion of oxygen and water permeability, enhancing photodynamic therapy (PDT) and T 1 signal, respectively. (4) Folic acid anchored on the outermost surface is able to target at specific cells for bimodal imaging and PDT. Proof of concept is provided in the in-vitro cell testing of H–MnO@mSiO2 (Ir)–FA NPs, which demonstrates excellent targeting specificity, minimal collateral damage and highly potent therapeutic effect.

Small, 2011

One-dimensional nanostructures containing heterojunctions by conjugated polymers, such as nanowir... more One-dimensional nanostructures containing heterojunctions by conjugated polymers, such as nanowires, are expected to greatly facilitate efficient charge transfer in bulk-heterojunction (BHJ) solar cells. Thus, a combined theoretical and experimental approach is pursued to explore spontaneous nanowire formation. A dissipative particle dynamics simulation is first performed to study the morphologies formed by rodlike polymers with various side-chain structures. The results surprisingly predict that conjugated polymers with branched side chains are well suited to form thermodynamically stable nanowires. Proof of this concept is provided via the design and synthesis of a branched polymer of regioregular poly(3-2-methylbutylthiophene) (P3MBT), which successfully demonstrates highly dense nanowire formation free from any stringent conditions and stratagies. In BHJ solar cells fabricated using a blend of P3MBT and [6,6]-phenyl-C71-butyric acid methyl ester (PC(71) BM), P3MBT polymers are self-organized into highly crystalline nanowires with a d(100) spacing of 13.30 Å. The hole mobility of the P3MBT:PC(71) BM (1:0.5 by weight) blend film reaches 3.83 × 10(-4) cm(2) V(-1) s(-1) , and the maximum incident photon-to-current efficiency reaches 68%. The results unambiguously prove the spontaneous formation of nanowires using solution-processable conjugated polymers with branched alkyl side chains in BHJ solar cells.

J. Mater. Chem. A, 2014

ABSTRACT A new medium-bandgap conjugated copolymers comprising a rigidly fused benzo[1,2-b:4,5-b&... more ABSTRACT A new medium-bandgap conjugated copolymers comprising a rigidly fused benzo[1,2-b:4,5-b']-dithiophene (BDT) unit and a fluorinated quinoxaline moiety through a thiophene π-spacer has been rationally designed and synthesized by Stille coupling polymerization and thoroughly evaluated for use as a donor material in bulk-heterojunction polymer solar cells (BHJ PSCs). A comprehensive study of the structure-function relationship in the PSCs was also explored. The PDBTQEH copolymer exhibits good solubility in a wide range of organic solvents and has a high hole mobility. Introduction of highly electronegative fluorine atoms to quinoxaline moiety further lowers both the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels of polymer, which is beneficial for attaining higher open-circuit voltage (Voc) and long-term stability. Conventional architecture BHJ PSCs using PBDTQEH:PC71BM (1:1, w/w) displays a high power conversion efficiency (PCE) of 5.90%. Compared with the same composition, device in the inverted configuration reveals a rather high PCE of 6.36% with a Voc of 0.78 V, a short-circuit current density (Jsc) of 12.72 mA cm-2, and a high fill factor (FF) of 64.3%. The inverted device also demonstrates outstanding air stability; without any capsulation, the solar efficiency of the device remains above 74% of the original value after storage in air for 1000 h.

Faraday Discuss., 2014

Neural stem cells (NSCs), which generate the main phenotypes of the nervous system, are multipote... more Neural stem cells (NSCs), which generate the main phenotypes of the nervous system, are multipotent cells and are able to differentiate into multiple cell types via external stimuli from the environment. The extraction, modification and re-application of NSCs have thus attracted much attention and raised hopes for novel neural stem cell therapies and regenerative medicine. However, few studies have successfully identified the distribution of NSCs in a live brain and monitored the corresponding extraction processes both in vitro and in vivo. To address those difficulties, in this study multi-functional uniform nanoparticles comprising an iron oxide core and a functionalized silica shell (Fe(3)O(4)@SiO(2)(FITC)-CD133, FITC: a green emissive dye, CD133: anti-CD133 antibody) have been strategically designed and synthesized for use as probe nanocomposites that provide four-in-one functionality, i.e., magnetic agitation, dual imaging (both magnetic resonance and optical) and specific targeting. It is shown that these newly synthesized Fe(3)O(4)@SiO(2)(FITC)-CD133 particles have clearly demonstrated their versatility in various applications. (1) The magnetic core enables magnetic cell collection and T(2) magnetic resonance imaging. (2) The fluorescent FITC embedded in the silica framework enables optical imaging. (3) CD133 anchored on the outermost surface is demonstrated to be capable of targeting neural stem cells for cell collection and bimodal imaging.

Nanoscale, Jan 28, 2015

The combination of a hollow mesoporous structure and a magnetic resonance (MR) contrast agent has... more The combination of a hollow mesoporous structure and a magnetic resonance (MR) contrast agent has shown its potential in simultaneous drug delivery and cell tracking applications. However, the preparation of this kind of nanocomposite is complicated and usually takes several days, which is unsuitable for scaled-up production. To overcome these hurdles, we report herein a facile method to synthesize iron oxide hydroxide functionalized hollow mesoporous silica spheres (FeOOH/HMSS) in a one-step manner. By carefully controlling the reaction kinetics of K2FeO4 in water, the gram-scale production of FeOOH/HMSS can be readily achieved at 60 °C for as short as 30 min. Most importantly, this synthetic process is also cost-effective and eco-friendly in both the precursor (K2FeO4 and H2O) and the product (FeOOH). The mechanism for the formation of a hollow structure was carefully investigated, which involves the synergetic effect of the surfactant CTAB and the side product KOH. Having outstan...

Journal of the American Chemical Society, 2013

A novel T1 agent, antiferromagnetic α-iron oxide-hydroxide (α-FeOOH) nanocolloids with a diameter... more A novel T1 agent, antiferromagnetic α-iron oxide-hydroxide (α-FeOOH) nanocolloids with a diameter of 2-3 nm, has been successfully prepared. These nanocolloids, together with a post synthetic strategy performed in mesoporous silica, are a great improvement over the low T1-weighted contrast common in traditional magnetic silica nanocomposites. The intrinsic antiferromagnetic goethite (α-FeOOH) shows very low magnetization (M(z)) of 0.05 emu g(-1) at H = 2 T at 300 K (0.0006 emu g(-1) for FeOOH/WMSN-PEG), which is 2 orders of magnitude smaller than any current ultrasmall iron oxide NPs (>5 emu g(-1)) reported to date, hence ensuring the low r2 (∝ Mz) (7.64 mM(-1) s(-1)) and r2/r1 ratio (2.03) at 4.7 T. These biodegradable α-FeOOH nanocolloids also demonstrate excellent in vitro cellular imaging and in vivo MR vascular and urinary trace imaging capability with outstanding biocompatibility, which is exceptionally well secreted by the kidney and not the liver as with most nanoparticles, opening up a new avenue for designing powerful antiferromagnetic iron T1 contrast agents.

Journal of Materials Chemistry, 2012

Angewandte Chemie International Edition, 2011

... 5. 5a M. Eichelbaum, BE Schmidt, H. Ibrahim, K. Rademann, Nanotechnology 2007, 18, 355702; ..... more ... 5. 5a M. Eichelbaum, BE Schmidt, H. Ibrahim, K. Rademann, Nanotechnology 2007, 18, 355702; ... 5b PD Jadzinsky, G. Calero, CJ Ackerson, DA Bushnell, RD Kornberg, Science 2007, 318, 430–433; ...

ACS Nano, 2011

Trifunctional uniform nanoparticles comprising a manganese nanocrystal core and a functionalized ... more Trifunctional uniform nanoparticles comprising a manganese nanocrystal core and a functionalized mesoporous silica shell (MnO@mSiO 2 (Ir)@PEG, where Ir is an emissive iridium complex and PEG is polyethylene glycol) have been strategically designed and synthesized. The T 1 signal can be optimized by forming hollow core (H-MnO@mSiO 2 (Ir)@PEG) via a novel and facile etching process, for which the mechanism has been discussed in detail. Systematic investigation on correlation for longitudinal relaxation (T 1 ) versus core shapes and shell silica porosity of the nanocomposites (MnO, H-MnO, MnO@SiO 2 , MnO@mSiO 2 , H-MnO@mSiO 2 ) has been carried out. The results show that the worm-like nanochannels in the mesoporous silica shell not only increase water permeability to the interior hollow manganese oxide core for T 1 signal but also enhance photodynamic therapy (PDT) efficacy by enabling the free diffusion of oxygen. Notably, the H-MnO@mSiO 2 (Ir)@PEG nanocomposite with promising r 1 relaxivity demonstrates its versatility, in which the magnetic core provides the capability for magnetic resonance imaging, while the simultaneous red phosphorescence and singlet oxygen generation from the Ir complex are capable of providing optical imaging and inducing apoptosis, respectively.

Journal of the American Chemical Society, Jan 26, 2016

Nano metal oxides are becoming widely used in industrial, commercial and personal products (semic... more Nano metal oxides are becoming widely used in industrial, commercial and personal products (semiconductors, optics, solar cells, catalysts, paints, cosmetics, sun-cream lotions, etc). However, the relationship of surface features (exposed planes, defects and chemical functionalities) with physiochemical properties is not well studied primarily due to lack of a simple technique for their characterization. In this study, solid state 31P MAS NMR is used to map surfaces on various ZnO samples with the assistance of trimethylphosphine (TMP) as a chemical probe. As similar to XRD giving structural information of a crystal, it is demonstrated that this new surface-fingerprint technique not only provides qualitative (chemical shift) but also quantitative (peak intensity) information on the concentration and distribution of cations and anions, oxygen vacancies and hydroxyl groups on various facets from a single deconvoluted 31P NMR spectrum. Based on this technique a new mechanism for photoc...

Chem. Commun., 2016

Near quantitative carbon yields of diesel-range alkanes were achieved from the hydrodeoxygenation... more Near quantitative carbon yields of diesel-range alkanes were achieved from the hydrodeoxygenation of triglycerides over Pd/NbOPO4 under mild conditions with no catalyst deactivation: catalyst characterization and theoretical calculations suggest that the high hydrodeoxygenation activity originated from the synergistic effect of Pd and strong Lewis acidity on the unique structure of NbOPO4.

Journal of Catalysis, 2016

Small, 2014

The room-temperature, aqueous-phase synthesis of iron-oxide nanoparticles (IO NPs) with glutathio... more The room-temperature, aqueous-phase synthesis of iron-oxide nanoparticles (IO NPs) with glutathione (GSH) is reported. The simple, one-step reduction involves GSH as a capping agent and tetrakis(hydroxymethyl)phosphonium chloride (THPC) as the reducing agent; GSH is an anti-oxidant that is abundant in the human body while THPC is commonly used in the synthesis of noble-metal clusters. Due to their low magnetization and good water-dispersibility, the resulting GSH-IO NPs, which are 3.72 ± 0.12 nm in diameter, exhibit a low r2 relaxivity (8.28 mm(-1) s(-1)) and r2/r1 ratio (2.28)--both of which are critical for T1 contrast agents. This, together with the excellent biocompatibility, makes these NPs an ideal candidate to be a T1 contrast agent. Its capability in cellular imaging is illustrated by the high signal intensity in the T1-weighted magnetic resonance imaging (MRI) of treated HeLa cells. Surprisingly, the GSH-IO NPs escape ingestion by the hepatic reticuloendothelial system, enabling strong vascular enhancement at the internal carotid artery and superior sagittal sinus, where detection of the thrombus is critical for diagnosing a stroke. Moreover, serial T1- and T2-weighted time-dependent MR images are resolved for a rat's kidneys, unveiling detailed cortical-medullary anatomy and renal physiological functions. The newly developed GSH-IO NPs thus open a new dimension in efforts towards high-performance, long-circulating MRI contrast agents that have biotargeting potential.

Materials Express, 2011

ABSTRACT We report the development of multi-functional uniform nanoparticles comprising a hollow ... more ABSTRACT We report the development of multi-functional uniform nanoparticles comprising a hollow manganese oxide core and a functionalized mesoporous silica shell (H–MnO@mSiO2 (Ir)@–FA, Ir: an emissive iridium complex, FA: folic acid) for use as theranostic nanocomposites that combine four-in-one functionality, i.e., dual imaging (both magnetic resonance and optical), specific targeting and therapy in a single unit. The H–MnO@mSiO2 (Ir)–FA nanoparticles (NPs) demonstrate its versatility in various applications. (1) The magnetic core provides the capability for T 1magnetic resonance imaging. (2) Phosphorescent iridium complex serves as both photosensitizer and the luminescent chromophore. (3) The nano-channels in the mesoporous silica shell increase the free diffusion of oxygen and water permeability, enhancing photodynamic therapy (PDT) and T 1 signal, respectively. (4) Folic acid anchored on the outermost surface is able to target at specific cells for bimodal imaging and PDT. Proof of concept is provided in the in-vitro cell testing of H–MnO@mSiO2 (Ir)–FA NPs, which demonstrates excellent targeting specificity, minimal collateral damage and highly potent therapeutic effect.

Small, 2011

One-dimensional nanostructures containing heterojunctions by conjugated polymers, such as nanowir... more One-dimensional nanostructures containing heterojunctions by conjugated polymers, such as nanowires, are expected to greatly facilitate efficient charge transfer in bulk-heterojunction (BHJ) solar cells. Thus, a combined theoretical and experimental approach is pursued to explore spontaneous nanowire formation. A dissipative particle dynamics simulation is first performed to study the morphologies formed by rodlike polymers with various side-chain structures. The results surprisingly predict that conjugated polymers with branched side chains are well suited to form thermodynamically stable nanowires. Proof of this concept is provided via the design and synthesis of a branched polymer of regioregular poly(3-2-methylbutylthiophene) (P3MBT), which successfully demonstrates highly dense nanowire formation free from any stringent conditions and stratagies. In BHJ solar cells fabricated using a blend of P3MBT and [6,6]-phenyl-C71-butyric acid methyl ester (PC(71) BM), P3MBT polymers are self-organized into highly crystalline nanowires with a d(100) spacing of 13.30 Å. The hole mobility of the P3MBT:PC(71) BM (1:0.5 by weight) blend film reaches 3.83 × 10(-4) cm(2) V(-1) s(-1) , and the maximum incident photon-to-current efficiency reaches 68%. The results unambiguously prove the spontaneous formation of nanowires using solution-processable conjugated polymers with branched alkyl side chains in BHJ solar cells.

J. Mater. Chem. A, 2014

ABSTRACT A new medium-bandgap conjugated copolymers comprising a rigidly fused benzo[1,2-b:4,5-b&... more ABSTRACT A new medium-bandgap conjugated copolymers comprising a rigidly fused benzo[1,2-b:4,5-b']-dithiophene (BDT) unit and a fluorinated quinoxaline moiety through a thiophene π-spacer has been rationally designed and synthesized by Stille coupling polymerization and thoroughly evaluated for use as a donor material in bulk-heterojunction polymer solar cells (BHJ PSCs). A comprehensive study of the structure-function relationship in the PSCs was also explored. The PDBTQEH copolymer exhibits good solubility in a wide range of organic solvents and has a high hole mobility. Introduction of highly electronegative fluorine atoms to quinoxaline moiety further lowers both the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels of polymer, which is beneficial for attaining higher open-circuit voltage (Voc) and long-term stability. Conventional architecture BHJ PSCs using PBDTQEH:PC71BM (1:1, w/w) displays a high power conversion efficiency (PCE) of 5.90%. Compared with the same composition, device in the inverted configuration reveals a rather high PCE of 6.36% with a Voc of 0.78 V, a short-circuit current density (Jsc) of 12.72 mA cm-2, and a high fill factor (FF) of 64.3%. The inverted device also demonstrates outstanding air stability; without any capsulation, the solar efficiency of the device remains above 74% of the original value after storage in air for 1000 h.

Faraday Discuss., 2014

Neural stem cells (NSCs), which generate the main phenotypes of the nervous system, are multipote... more Neural stem cells (NSCs), which generate the main phenotypes of the nervous system, are multipotent cells and are able to differentiate into multiple cell types via external stimuli from the environment. The extraction, modification and re-application of NSCs have thus attracted much attention and raised hopes for novel neural stem cell therapies and regenerative medicine. However, few studies have successfully identified the distribution of NSCs in a live brain and monitored the corresponding extraction processes both in vitro and in vivo. To address those difficulties, in this study multi-functional uniform nanoparticles comprising an iron oxide core and a functionalized silica shell (Fe(3)O(4)@SiO(2)(FITC)-CD133, FITC: a green emissive dye, CD133: anti-CD133 antibody) have been strategically designed and synthesized for use as probe nanocomposites that provide four-in-one functionality, i.e., magnetic agitation, dual imaging (both magnetic resonance and optical) and specific targeting. It is shown that these newly synthesized Fe(3)O(4)@SiO(2)(FITC)-CD133 particles have clearly demonstrated their versatility in various applications. (1) The magnetic core enables magnetic cell collection and T(2) magnetic resonance imaging. (2) The fluorescent FITC embedded in the silica framework enables optical imaging. (3) CD133 anchored on the outermost surface is demonstrated to be capable of targeting neural stem cells for cell collection and bimodal imaging.

Nanoscale, Jan 28, 2015

The combination of a hollow mesoporous structure and a magnetic resonance (MR) contrast agent has... more The combination of a hollow mesoporous structure and a magnetic resonance (MR) contrast agent has shown its potential in simultaneous drug delivery and cell tracking applications. However, the preparation of this kind of nanocomposite is complicated and usually takes several days, which is unsuitable for scaled-up production. To overcome these hurdles, we report herein a facile method to synthesize iron oxide hydroxide functionalized hollow mesoporous silica spheres (FeOOH/HMSS) in a one-step manner. By carefully controlling the reaction kinetics of K2FeO4 in water, the gram-scale production of FeOOH/HMSS can be readily achieved at 60 °C for as short as 30 min. Most importantly, this synthetic process is also cost-effective and eco-friendly in both the precursor (K2FeO4 and H2O) and the product (FeOOH). The mechanism for the formation of a hollow structure was carefully investigated, which involves the synergetic effect of the surfactant CTAB and the side product KOH. Having outstan...

Journal of the American Chemical Society, 2013

A novel T1 agent, antiferromagnetic α-iron oxide-hydroxide (α-FeOOH) nanocolloids with a diameter... more A novel T1 agent, antiferromagnetic α-iron oxide-hydroxide (α-FeOOH) nanocolloids with a diameter of 2-3 nm, has been successfully prepared. These nanocolloids, together with a post synthetic strategy performed in mesoporous silica, are a great improvement over the low T1-weighted contrast common in traditional magnetic silica nanocomposites. The intrinsic antiferromagnetic goethite (α-FeOOH) shows very low magnetization (M(z)) of 0.05 emu g(-1) at H = 2 T at 300 K (0.0006 emu g(-1) for FeOOH/WMSN-PEG), which is 2 orders of magnitude smaller than any current ultrasmall iron oxide NPs (>5 emu g(-1)) reported to date, hence ensuring the low r2 (∝ Mz) (7.64 mM(-1) s(-1)) and r2/r1 ratio (2.03) at 4.7 T. These biodegradable α-FeOOH nanocolloids also demonstrate excellent in vitro cellular imaging and in vivo MR vascular and urinary trace imaging capability with outstanding biocompatibility, which is exceptionally well secreted by the kidney and not the liver as with most nanoparticles, opening up a new avenue for designing powerful antiferromagnetic iron T1 contrast agents.

Journal of Materials Chemistry, 2012

Angewandte Chemie International Edition, 2011

... 5. 5a M. Eichelbaum, BE Schmidt, H. Ibrahim, K. Rademann, Nanotechnology 2007, 18, 355702; ..... more ... 5. 5a M. Eichelbaum, BE Schmidt, H. Ibrahim, K. Rademann, Nanotechnology 2007, 18, 355702; ... 5b PD Jadzinsky, G. Calero, CJ Ackerson, DA Bushnell, RD Kornberg, Science 2007, 318, 430–433; ...

ACS Nano, 2011

Trifunctional uniform nanoparticles comprising a manganese nanocrystal core and a functionalized ... more Trifunctional uniform nanoparticles comprising a manganese nanocrystal core and a functionalized mesoporous silica shell (MnO@mSiO 2 (Ir)@PEG, where Ir is an emissive iridium complex and PEG is polyethylene glycol) have been strategically designed and synthesized. The T 1 signal can be optimized by forming hollow core (H-MnO@mSiO 2 (Ir)@PEG) via a novel and facile etching process, for which the mechanism has been discussed in detail. Systematic investigation on correlation for longitudinal relaxation (T 1 ) versus core shapes and shell silica porosity of the nanocomposites (MnO, H-MnO, MnO@SiO 2 , MnO@mSiO 2 , H-MnO@mSiO 2 ) has been carried out. The results show that the worm-like nanochannels in the mesoporous silica shell not only increase water permeability to the interior hollow manganese oxide core for T 1 signal but also enhance photodynamic therapy (PDT) efficacy by enabling the free diffusion of oxygen. Notably, the H-MnO@mSiO 2 (Ir)@PEG nanocomposite with promising r 1 relaxivity demonstrates its versatility, in which the magnetic core provides the capability for magnetic resonance imaging, while the simultaneous red phosphorescence and singlet oxygen generation from the Ir complex are capable of providing optical imaging and inducing apoptosis, respectively.

Journal of the American Chemical Society, Jan 26, 2016

Nano metal oxides are becoming widely used in industrial, commercial and personal products (semic... more Nano metal oxides are becoming widely used in industrial, commercial and personal products (semiconductors, optics, solar cells, catalysts, paints, cosmetics, sun-cream lotions, etc). However, the relationship of surface features (exposed planes, defects and chemical functionalities) with physiochemical properties is not well studied primarily due to lack of a simple technique for their characterization. In this study, solid state 31P MAS NMR is used to map surfaces on various ZnO samples with the assistance of trimethylphosphine (TMP) as a chemical probe. As similar to XRD giving structural information of a crystal, it is demonstrated that this new surface-fingerprint technique not only provides qualitative (chemical shift) but also quantitative (peak intensity) information on the concentration and distribution of cations and anions, oxygen vacancies and hydroxyl groups on various facets from a single deconvoluted 31P NMR spectrum. Based on this technique a new mechanism for photoc...