N-Doping Induced Lattice Expansion of 1D Template Confined Ultrathin MoS2 Sheets to Significantly Enhance Lithium Polysulfides Redox Kinetics for Li-S Battery.

Preparing MoS2 -based materials with reasonable structure and catalytic activity to enhance the sluggish kinetics of lithium polysulfides (LiPSs) conversion is of great significance for Li-S batteries (LSBs) but still remain a challenge. Hence, hollow nanotubes composed of N-doped ultrathin MoS2 nanosheets (N-MoS2 NHTs) are fabricated as efficient S hosts for LSBs by using CdS nanorods as a sacrifice template. Characterization and theoretical results show that the template effectively inhibits the excessive growth of MoS2 sheets, and N doping expands the interlayer spacing and modulates the electronic structure, thus accelerating the mass/electron transfer and enhancing the LiPSs adsorption and transformation. Benefiting from the merits, the N-MoS2 NHTs@S cathode exhibits an excellent initial capacity of 887.8 mAh g-1 and stable cycling performances with capacity fading of only 0.0436% per cycle at 1.0 C (500 cycles). Moreover, even at high S loading that of 7.5 mg cm-2 , the N-MoS2 NHTs@S cathode also presents initial excellent areal capacity of 7.80 mAh cm-2 at 0.2 C. This study offers feasible guidance for designing advanced MoS2 -based cathode materials in LSBs.

Engineering Amorphous/Crystalline Ru(OH)3/CoFe-Layered Double Hydroxide for Hydrogen Evolution at 1000 mA cm-2.

For large-scale industrial applications, it is highly desirable to create effective, economical electrocatalysts with long-term stability for the hydrogen evolution reaction (HER) at a large current density. Herein, we report a unique motif with crystalline CoFe-layered hydroxide (CoFe-LDH) nanosheets enclosed by amorphous ruthenium hydroxide (a-Ru(OH)3/CoFe-LDH) to realize the efficient hydrogen production at 1000 mA cm-2, with a low overpotential of 178 mV in alkaline media. During the continuous HER process for 40 h at such a large current density, the potential remains almost constant with only slight fluctuations, indicating good long-term stability. The remarkable HER performance can be attributed to the charge redistribution caused by abundant oxygen vacancies in a-Ru(OH)3/CoFe-LDH. The increased electron density of states lowers the charge-transfer resistance and promotes the formation and release of H2 molecules. The water-splitting electrolyzer with a-Ru(OH)3/CoFe-LDH as both an anode and a cathode in 1.0 M KOH demonstrates stable hydrogen production and a 100% faradic efficiency. The design strategy of interface engineering in this work will inspire the design of practical electrocatalysts for water splitting on an industrial scale.

Cobalt-Carbon nanotubes supported on V2O3 nanorods as sulfur hosts for High-performance Lithium-Sulfur batteries.

Exploring advanced sulfur cathode materials with high catalytic activity to accelerate the slow redox reactions of lithium polysulfides (LiPSs) is of great significance for lithium-sulfur batteries (LSBs). In this study, a coral-like hybrid composed of cobalt nanoparticle-embedded N-doped carbon nanotubes supported by Vanadium (III) oxide (V2O3) nanorods (Co-CNTs/C @V2O3) was designed as an efficient sulfur host using a simple annealing process. Characterization combined with electrochemical analysis confirmed that the V2O3 nanorods exhibited enhanced LiPSs adsorption capacity, and the in situ grown short-length Co-CNTs improved electron/mass transport and enhanced the catalytic activity for conversion to LiPSs. Owing to these merits, the S@Co-CNTs/C@V2O3 cathode exhibits effective capacity and cycle lifetime. Its initial capacity was 864 mAh g-1 at 1.0C and remained at 594 mAh g-1 after 800cycles with a decay rate of 0.039%. Furthermore, even at a high sulfur loading (4.5 mg cm-2), S@Co-CNTs/C@V2O3 also shows acceptable initial capacity of 880 mAh g-1 at 0.5C. This study provides new ideas for preparing long-cycle S-hosting cathodes for LSBs.

Confined Co9S8 nanocrystals into N/S-Co-doped carbon nanofibers as a chainmail-like electrocatalyst for high-performance lithium-sulfur batteries with high sulfur loading.

Accelerating phase transposition efficiency of lithium polysulfides (LiPSs) to L2S and hampering the solution of LiPSs are the keys to stabilizing lithium-sulfur (Li-S) batteries. Hence, the sulfiphilic ultrafine Co9S8 nanoparticles embedded lithiophilic N, S co-doping carbon nanofibers (Co9S8/NSCNF) are prepared via the dual-template method, which are then used as sulfur host in Li-S batteries. Particularly, the double active sites (Co9S8 and N, S) in Co9S8/NSCNF are prone to form "Co-S", "Li-O" or "Li-N" bonds, and then simultaneously improving the chemisorption and interface transposition capability of LiPSs. In case of the S@ Co9S8/NSCNF composites with high sulfur loading of 89% are employed as cathode, the cell possesses optimized "sulfiphilicity" and "lithiophilicity", which achieves remarkable sulfur electrochemistry, including outstanding reversibility of 816.8mAhg-1 over 500 cycles at 1.0C, excellent rate property of 742.2mAhg-1at 5.0C, and long-term cycling with a low attenuation of 0.011% per cycle over 1800 cycles at 3.0C. Impressively, a remarkable areal capacity of 11.51mAhcm-2 is retained under the sulfur loading of 15.3 mg cm-2 for 50 cycles. This research will deepen the understanding of the complex LiPSs interface transposition procedure and provide new ideas for the design of new host materials.

Crystal Surface Engineering Induced Active Hexagonal Co2 P-V2 O3 for Highly Stable Lithium-Sulfur Batteries.

Purposeful control of the highly active crystal planes is an effective strategy to improve the nanocrystalline catalytic activity. Therefore, Co2 P nanocrystals with high exposure of (211) lattice plane loaded at 2D hexagonal V2 O3 nanosheets (H-Co2 P-V2 O3 ) are designed via the control of morphology. After optimization, this H-Co2 P-V2 O3 boosts the redox kinetics of lithium polysulfides (LiPSs) in lithium-sulfur batteries (LSBs), which is due to the increase of the Co-active sites by exposing more (211) lattice planes of Co2 P, and the high adsorption and catalysis characteristic of H-Co2 P-V2 O3 for the conversion of LiPSs into LSBs. In the case of modification separator by H-Co2 P-V2 O3 composite, the battery achieves an outstanding reversibility of 876.9 mAh g-1 over 500 cycles at 1 C, a superior rate property of 611.5 mAh g-1 at 8 C, and a long-term cycling performance with a low attenuation of 0.04% per cycle over 1000 cycles at 4 C for LSBs. Impressively, a remarkable areal capacity of 12.38 mAh cm-2 is retained under the high sulfur loading of 14.5 mg cm-2 after 100 cycles. It is believed that the crystal surface engineering provides guidance to further improve the electrochemical performance of the LSB field.

yMoO42- modified amorphous Co(PO3)2 cubes as an efficient bifunctional electrocatalyst for alkaline overall water splitting.

The exploration of efficient bifunctional electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) under alkaline conditions is an importantway to promote the development of electrolytic water technology. Herein, the reduced graphene oxide-supported MoO42- modified amorphous cobalt metaphosphate cubes (a-Co(PO3)2/MoO4/rGO) as bifunctional OER/HER catalyst is prepared by anion exchange and phosphating, using the Prussian blue analogue (PBA) as a precursor. The resulting composite exhibits the low overpotentials (η) that of 290 and 50 mV for OER and HER in 1.0 M KOH solution at 10 mA cm-2, respectively. The electrochemical test and density functional theory (DFT) results reveal that the MoO42--modified optimizes the adsorption/desorption energy of H* of Co(PO3)2, thus enhance the HER activity. Benefiting from efficient HER and OER performances, an efficient and stable alkaline water electrolysis operation using a-Co(PO3)2/MoO4/rGO used as bifunctional catalyst can be carried out, which can deliver a current density (j) of 20 mA cm-2 at 1.65 V cell voltage and work continuously for 24 h.

Rational Design of the Lotus-Like N-Co2 VO4 -Co Heterostructures with Well-Defined Interfaces in Suppressing the Shuttle Effect and Dendrite Growth in Lithium-Sulfur Batteries.

The shuttle effect caused by soluble lithium polysulfides (LiPSs) and intrinsic slow electrochemical transformation from LiPSs to Li2 S/Li2 S2 will induce undesirable cycling performance, which is the primary obstruct limiting the practical applications of lithium-sulfur (Li-S) batteries. Here a convenient method is designed to fabricate the 2D louts-like N-Co2 VO4 -Co heterostructures with well-abundant interfaces and oxygen vacancies (Vo ), endowing the materials with both "sulfiphilic" and "lithiophilic" features. When employed as the modification layer coated on commercial Celgard 2400 separator, the as-prepared N-Co2 VO4 -Co/PP with synergistic adsorption-electrocatalysis effects achieves desirable sulfur electrochemistry, thus showing a high initial discharge capacity of 1466.4 mAh g-1 at 0.1 C and stable cycle life with a fade rate of 0.03% per cycle over 1000 cycle at 3.0 C. Moreover, a superior areal capacity of 12.84 mAh cm-2 is preserved under high sulfur loading of 14.3 mg cm-2 .

Amorphous CoP nanoparticle composites with nitrogen-doped hollow carbon nanospheres for synergetic anchoring and catalytic conversion of polysulfides in Li-S batteries.

The commercial viability of Li-S batteries was obstructed by short cycle life and poor capability owing to slow redox kinetics and polysulfide shuttle effect. To tackle these challenges, the amorphous CoP anchored on N-doped carbon nanospheres with hollow porous structures (CoP/HCS) has been synthesized as a superior sulfur host via a facial pyrolysis approach. The debilitating effect would be hampered during the cycling processing resulting from two reasons:(1) the powerful chemical anchoring between unsaturated Co and Li-polysulfides, (2) the remarkable adaption of volume variation originating from the hollow porous architectures. The amorphous CoP nanoparticles not only catalyze the transformation of lithium polysulfides as electrocatalyst, but also acquired a high sulfur loading as sulfur host materials. More importantly, the synergistic incorporation of CoP and HCS improved the inherit low conductivity by anchoring on the N-doped carbon hollow, thus leading to excellent performance for Li-S batteries. Benefiting from these advantages, the amorphous CoP/HCS-based sulfur electrodes exhibited outstanding rate performance (685.6 mAh g-1 at 3C), excellent long-cycling stability with a low capacity decay of only 0.03% per cycle over 1000 cycles at 2C, and a high areal capacity of 5.16 mAh cm-2 under high sulfur loading.

Fe(III) Ions-Assisted Aniline Polymerization Strategy to Nitrogen-Doped Carbon-Supported Bimetallic CoFeP Nanospheres as Efficient Bifunctional Electrocatalysts toward Overall Water Splitting.

It remains an urgent demand and challenging task to design and fabricate efficient, stable, and inexpensive catalysts toward sustainable electrochemical water splitting for hydrogen production. Herein, we explored the use of Fe(III) ion-assisted aniline polymerization strategy to embed bimetallic CoFeP nanospheres into the nitrogen-doped porous carbon framework (referred CoFeP-NC). The as-prepared CoFeP-NC possesses excellent hydrogen evolution reaction (HER) performance with the small overpotential (η10) of 81 mV and 173 mV generated at a current density of 10 mA cm-2 in acidic and alkaline media, respectively. Additionally, it can also efficiently catalyze water oxidation (OER), which shows an ideal overpotential (η10) of 283 mV in alkaline electrolyte (pH = 14). The remarkable catalytic property of CoFeP-NC mainly stems from the strong synergetic effects of CoFeP nanospheres and carbon network. On the one hand, the interaction between the two can make better contact between the electrolyte and the catalyst, thereby providing a large number of available active sites. On the other hand, it can also form a network to offer better durability and electrical conductivity (8.64 × 10-1 S cm-1). This work demonstrates an efficient method to fabricate non-noble electrocatalyst towards overall water splitting, with great application prospect.

Advanced Electrocatalysts with Single-Metal-Atom Active Sites.

Electrocatalysts with single metal atoms as active sites have received increasing attention owing to their high atomic utilization efficiency and exotic catalytic activity and selectivity. This review aims to provide a comprehensive summary on the recent development of such single-atom electrocatalysts (SAECs) for various energy-conversion reactions. The discussion starts with an introduction of the different types of SAECs, followed by an overview of the synthetic methodologies to control the atomic dispersion of metal sites and atomically resolved characterization using state-of-the-art microscopic and spectroscopic techniques. In recognition of the extensive applications of SAECs, the electrocatalytic studies are dissected in terms of various important electrochemical reactions, including hydrogen evolution reaction (HER), oxygen evolution reaction (OER), oxygen reduction reaction (ORR), carbon dioxide reduction reaction (CO2RR), and nitrogen reduction reaction (NRR). Examples of SAECs are deliberated in each case in terms of their catalytic performance, structure-property relationships, and catalytic enhancement mechanisms. A perspective is provided at the end of each section about remaining challenges and opportunities for the development of SAECs for the targeted reaction.

Facile synthesis of carboxymethyl cellulose sulfur quantum dots for live cell imaging and sensitive detection of Cr(VI) and ascorbic acid.

Nowadays the synthesis of stable fluorescent sulfur quantum dots (SQDs) remains a big challenge. Herein, the utilization of carboxymethyl cellulose (CMC) to synthesis of SQDs is reported. Benefiting from the unique composition and structure of CMC macromolecule, the resulted CMC-SQDs simultaneously show high aqueous dispersibility and stability, tunable emission, stable fluorescence and low cytotoxicity, which make them promising for working as a fluorescent probe. Fluorescence detection experiments suggested that the CMC-SQDs could serve as a fluorescence on-off-on switch to sensitive and selective detection of Cr(VI) and ascorbic acid (AA) based on the inner filter effect (IFE). The limit of detection towards Cr(VI) and AA can reach 0.024 and 0.18 µM with linear range of 0.5-225 and 1-300 µM, respectively, which compares favorably to other reported fluorescent probes. In addition, the employment of fluorescent CMC-SQDs for practical detection of Cr(VI) and AA was also studied.

Unravelling the formation mechanism of alkynyl protected gold clusters: a case study of phenylacetylene stabilized Au144 molecules.

Despite recent progress in the preparation of alkynyl protected Au clusters with molecular purity (e.g., Na[Au25(C[triple bond, length as m-dash]CAr)18, Ar = 3,5-(CF3)2C6H3-, Au36(C[triple bond, length as m-dash]CPh)24, Au44(C[triple bond, length as m-dash]CPh)28, and Au144(C[triple bond, length as m-dash]CAr)60, Ar = 2-F-C6H4-), the formation mechanism still remains elusive. Herein, a new molecule-like alkynyl Au cluster was successfully prepared, and its formula was determined as Au144(PA)60 (PA = PhC[triple bond, length as m-dash]C-, phenylacetylene). In the formation of Au144(PA)60, the introduction of ethanol in post-synthesis treatment to manipulate the aggregation state of the precursor was found to play a critical role in producing the Au144 clusters. During the Au144(PA)60 formation process, the contents of PA, (PA)2 and (PA)4 were monitored by absorbance and gas chromatography-mass spectrometry (GC-MS), disclosing that Au144(PA)60 molecules were generated in sync with (PA)4. Finally, the formation mechanism of Au144(PA)60 molecules has been tentatively proposed, of which three major stages are involved. This study can shed light on the formation mechanism that may be exploited for the precise control of the synthesis of alkynyl protected coinage metal clusters.

N, S-codoped CNTs supported Co4S3 nanoparticles prepared by using CdS nanorods as sulfur sources and hard templates: An efficient catalyst for reversible oxygen electrocatalysis.

Non-precious efficient bifunctional catalysts towards oxygen reduction/evolution reactions (ORR/OER) are highly desired to enable the widespread application of rechargeable Zn-air batteries (r-ZABs). Herein, Prussian blue analogues (PBA) anchored on CdS nanorods (CdS NRs) pre-coated with polydopamine (PDA) are utilized as precursors to prepare ultrafine Co4S3 nanoparticles supported on N, S-codoped CNTs (Co4S3@N,S-CNT), where CdS NRs are served as sulfur sources and hard templates. After pyrolysis, the resulting Co4S3@N,S-CNT-800 shows a high specific surface area of 142.4 m2 g-1, together with merely 0.780 V difference between the OER potential at 10 mA cm-2 and the ORR potential at 3 mA cm-2. The Co4S3@N,S-CNT-800 based air cathode displays a higher discharge capacity of 787 mAh gZn-1 at 10 mA cm-2, a higher output power density of 154 mW cm-2, better working stability, as well as a lower charge-discharge voltage gap than the Pt/C + RuO2 based air electrode at various working current density. The remarkable oxygen reversible catalytic activities are mainly attributed to the presence of a thin layer of mesoporous carbon on partial sections of the open-end N,S-CNTs, which not only shortens the mass diffusion length but also prevents N,S-CNTs from excessively bundling to maximize the exposure of Co4S3 nanocrystallites and graphitized carbon skeletons with N or S heteroatoms.

N,S-Codoped hierarchical porous carbon spheres embedded with cobalt nanoparticles as efficient bifunctional oxygen electrocatalysts for rechargeable zinc-air batteries.

Rational design and fabrication of cost-effective, efficient bifunctional electrocatalysts is fundamentally important for the air cathode of metal-air batteries. Herein, a Co(ii) ion-driven self-assembly strategy is described for the synthesis of cobalt-based nanostructured transition metal compounds (Co-NTMCs) embedded in nitrogen and sulfur codoped hierarchical porous carbon submicrospheres (Co-NTMCs@NSC), where condensation of thiourea-ethylenediamine-formaldehyde resin (TEFR) is induced by Co(ii) ions which is simultaneously assembled with polydopamine to form a multifunctional precursor through coordinated interaction. The resulting Co-NTMCs@NSC sample comprises abundant hierarchical porous textures, a high content of active cobalt species including the nanoparticles of Co, Co3O4 and amorphous CoSx, and a considerable amount of defective structures. These characteristics lead to remarkable oxygen electrocatalytic activities, with a half-wave potential of +0.833 V vs. RHE, which is comparable to that of commercial Pt/C for the oxygen reduction reaction (ORR), and a lower overpotential of 284 mV than RuO2 at 10 mA·cm-2 for the oxygen evolution reaction (OER) in alkaline media. Furthermore, its operational stability is also much higher than that of commercial RuO2 and Pt/C catalysts. When used as a breathing air electrode for Zn-air batteries, Co-NTMCs@NSC shows a higher open-circuit voltage (1.509 V), higher discharge power density (262 mW cm-2) and better charge-discharge reversibility than commercial Pt/C. The results from the present work suggest that controlled assembly of functional polymers may be exploited for the preparation of doped carbon/metal nanoparticle nanocomposites as viable, high-performance catalysts for electrochemical energy technologies.

Hierarchically Porous Carbon Plates Derived from Wood as Bifunctional ORR/OER Electrodes.

Porous carbon electrodes have emerged as important cathode materials for metal-air battery systems. However, most approaches for fabricating porous carbon electrodes from biomass are highly energy inefficient as they require the breaking down of the biomass and its subsequent reconstitution into powder-like carbon. Here, enzymes are explored to effectively hydrolyze the partial cellulose in bulk raw wood to form a large number of nanopores, which helps to maximally expose the inner parts of the raw wood to sufficiently dope nitrogen onto the carbon skeletons during the subsequent pyrolysis process. The resulting carbons exhibit excellent catalytic activity with respect to the oxygen reduction and oxygen evolution reactions. As-fabricated cellulose-digested, carbonized wood plates are mechanically strong, have high conductivity, and contain a crosslinked network and natural ion-transport channels and can be employed directly as metal-free electrodes without carbon paper, polymer binders, or carbon black. When used as metal-free cathodes in zinc-air batteries, they result in a specific capacity of 801 mA h g-1 and an energy density of 955 W h kg-1 with the long-term stability of the batteries being as high as 110 h. This work paves the way for the ready conversion of abundant biomass into high-value engineering products for energy-related applications.

Hierarchically Structured Co(OH)2/CoPt/N-CN Air Cathodes for Rechargeable Zinc-Air Batteries.

For the realization of the large-scale deployment of rechargeable Zn-air batteries, it is crucial to develop cost-effective, efficient, and stable bifunctional electrocatalysts for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In this work, an integrated electrocatalyst consisting of Co(OH)2/CoPt/N-CN was developed to enable both ORR and OER reactions for Zn-air batteries. The hierarchical Co(OH)2/CoPt/N-CN electrocatalyst has desirable electrochemical properties, with comparable activity and better durability than commercial Pt/C for ORR and improved activity and long-term stability than commercial IrO2 catalyst for OER. When implemented as air-cathode for rechargeable Zn-air batteries, Co(OH)2/CoPt/N-CN exhibited a high power-density of 171 mW cm-2, a specific capacity of 812 mA h g-1, and a robust cycling life. Interestingly, the hierarchical structure remained intact upon charge and discharge tests, suggesting potential long-term use in the Zn-air battery technology. The material development strategy presented here can enrich the toolbox for the design and construction of cost-effective, efficient, and robust bi-functional electrocatalysts for ORR and OER toward rechargeable Zn-air battery applications.

Conducting Polymers Crosslinked with Sulfur as Cathode Materials for High-Rate, Ultralong-Life Lithium-Sulfur Batteries.

Low electrical conductivity and a lack of chemical confinement are two major factors that limit the rate performances and cycling stabilities of cathode materials in lithium-sulfur (Li-S) batteries. Herein, sulfur is copolymerized with poly(m-aminothiophenol) (PMAT) nanoplates through inverse vulcanization to form the highly crosslinked copolymer cp(S-PMAT) in which approximately 80 wt % of the feed sulfur is bonded chemically to the thiol groups of PMAT. A cp(S-PMAT)/C-based cathode exhibits a high discharge capacity of 1240 mAh g-1 at 0.1 C and remarkable rate capacities of 880 mAh g-1 at 1 C and 600 mAh g-1 at 5 C. Moreover, it can retain a capacity of 495 mAh g-1 after 1000 deep discharge-charge cycles at 2 C; this corresponds to a retention of 66.9 % and a decay rate of only 0.040 % per cycle. Such a remarkable rate performance is attributed to the highly conductive pathways of PMAT nanoplates, and the excellent cycling stability is ascribed mainly to the chemical confinement of sulfur through a large number of stable covalent bonds between sulfur and the thiol groups of PMAT. The results suggest that this strategy is a viable paradigm for the design and engineering of conducting polymers with reactive functional groups as effective electrode materials for high-performance Li-S batteries.

Graphene Composites with Cobalt Sulfide: Efficient Trifunctional Electrocatalysts for Oxygen Reversible Catalysis and Hydrogen Production in the Same Electrolyte.

Nitrogen and sulfur-codoped graphene composites with Co9 S8 (NS/rGO-Co) are synthesized by facile thermal annealing of graphene oxides with cobalt nitrate and thiourea in an ammonium atmosphere. Significantly, in 0.1 m KOH aqueous solution the best sample exhibits an oxygen evolution reaction (OER) activity that is superior to that of benchmark RuO2 catalysts, an oxygen reduction reaction (ORR) activity that is comparable to that of commercial Pt/C, and an overpotential of only -0.193 V to reach 10 mA cm-2 for hydrogen evolution reaction (HER). With this single catalyst for oxygen reversible electrocatalysis, a potential difference of only 0.700 V is observed in 0.1 m KOH solution between the half-wave potential in ORR and the potential to reach 10 mA cm-2 in OER; in addition, an overpotential of only 450 mV is needed to reach 10 mA cm-2 for full water splitting in the same electrolyte. The present trifunctional catalytic activities are markedly better than leading results reported in recent literature, where the remarkable trifunctional activity is attributed to the synergetic effects between N,S-codoped rGO, and Co9 S8 nanoparticles. These results highlight the significance of deliberate structural engineering in the preparation of multifunctional electrocatalysts for versatile electrochemical reactions.

Impacts of interfacial charge transfer on nanoparticle electrocatalytic activity towards oxygen reduction.

Polymer electrolyte membrane fuel cells represent a next-generation power supply technology that may be used in a diverse range of applications. Towards this end, the rational design and engineering of functional nanomaterials as low-cost, high-performance catalysts is of critical significance in the wide-spread commercialization of fuel cell technology. One major bottleneck is the oxygen reduction reaction (ORR) at the cathode. Whereas platinum-based nanoparticles have been used as the catalysts of choice, further engineering of the nanoparticles is urgently needed to enhance the catalytic performance and concurrently reduce the costs. Extensive research has also been extended to non-platinum metals or even metal-free nanocatalysts that may be viable alternatives to platinum. In this review article, we will summarize recent progress in these areas of research within the context of interfacial electron transfer: (a) interactions between metal elements in alloy nanoparticles, (b) metal-ligand interfacial bonding interactions, (c) metal-carbon substrate interactions, and (d) heteroatom doping of graphitic carbons. Results have shown that ready manipulation of the electronic interactions between the catalyst surface and oxygen species may serve as a fundamental mechanism for the optimization of the catalytic performance.

Bioreduction of Precious Metals by Microorganism: Efficient Gold@N-Doped Carbon Electrocatalysts for the Hydrogen Evolution Reaction.

The uptake of precious metals from electronic waste is of environmental significance and potential commercial value. A facile bioreductive synthesis is described for Au nanoparticles (ca. 20 nm) supported on N-doped carbon (Au@NC), which was derived from Au/Pycnoporus sanguineus cells. The interface and charge transport between Au and N-doped carbon were confirmed by HRTEM and XPS. Au@NC was employed as an electrocatalyst for the hydrogen evolution reaction (HER), exhibiting a small onset potential of -54.1 mV (vs. RHE), a Tafel slope of 76.8 mV dec(-1) , as well as robust stability in acidic medium. Au@NC is a multifunctional electrocatalyst, which demonstrates high catalytic activity in the oxygen reduction reaction (ORR), as evidenced by an onset potential of +0.97 V, excellent tolerance toward methanol, and long-term stability. This work exemplifies dual recovery of precious Au and fabrication of multifunctional electrocatalysts in an environmentally benign and application-oriented manner.