The development of efficient and highly durable materials for renewable energy conversion devices is crucial to the future of clean energy demand. Herein, cage‐like quasihexagonal structured platinum nanodendrites decorated over the transition metal chalcogenide core (CoS2)‐N‐doped graphene oxide (PtNDs@CoS2‐NrGO) through optimized shape engineering and structural control technology are fabricated. The prepared electrocatalyst of PtNDs@CoS2‐NrGO is effectively used as anodic catalyst for alcohol oxidation in direct liquid alcohol fuel cells. Notably, the prepared PtNDs@CoS2‐NrGO exhibits superior electrocatalytic performance toward alcohol oxidation with higher oxidation peak current densities of 491.31, 440.25, and 438.12 mA mgpt–1 for (methanol) C1, (ethylene glycol) C2, and (glycerol) C3 fuel electrolytes, respectively, as compared to state‐of‐the‐art Pt‐C in acidic medium. The electro‐oxidation durability of PtNDs@CoS2‐NrGO is investigated through cyclic voltammetry and chronoamperometry tests, which demonstrate excellent stability of the electrocatalyst toward various alcohols. Furthermore, the surface and adsorption energies of PtNDs and CoS2 are calculated using density functional theory along with the detailed bonding analysis. Overall, the obtained results emphasize the advances in effective precious material utilization and fabricating techniques of active electrocatalysts for direct alcohol oxidation fuel cell applications.

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/advs.202105344

Quasihexagonal Platinum Nanodendrites Decorated over CoS2‐N‐Doped Reduced Graphene Oxide for Electro‐Oxidation of C1‐, C2‐, and C3‐Type Alcohols

Anion dependency of spinel type cobalt catalysts for efficient overall water splitting in an acid medium

The development of novel electrocatalysts with high efficiency, low cost, and high stability to replace platinum group metal (PGM) electrocatalysts is essential for realizing sustainable energy applications. In this study, we synthesized a tetrafunctional electrocatalyst comprising NiFe layered double-hydroxide (LDH) nanosheets anchored on carbon-nanotube-grafted (CNT), Co3O4-embedded, and N-doped porous carbon matrices (NC) derived from zeolitic imidazolate frameworks (NiFe LDHCNT-Co3O4/NC). This electrocatalyst exhibited superior performance to PGM electrocatalysts in the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and carbon dioxide reduction reaction (CO2RR). The linear sweep voltammetry study showed that the NiFe LDHCNT-Co3O4/NC demonstrated superior performance (Eonset = 0.85 V and E1/2 = 0.79 V for ORR; Ej=10 = 1.63 V for OER; overpotential = 0.84 V) comparing to the benchmarks of Pt/C and RuO2. A rechargeable Zn–air battery (ZAB) is used to verify the performance of the developed electrocatalyst in the ORR and OER; the ZAB exhibited an ultralow charge–discharge voltage gap (0.74 V) and excellent stability (104 cycles, >1600 [email protected] mA cm−2). Overall water splitting (OWS) is performed to verify the performance of the developed electrocatalyst in the OER and HER. The adopted OWS device exhibited a long and stable process (1.6 [email protected] mA cm−1, 700 h). CO2 conversion is investigated for evaluating the HER and CO2RR, and an 80% faradaic efficiency of CO production and high stability are obtained (166 mA cm−2@−1.09 V). We think that the synergistic effect of the NiFe LDHs, Co3O4 nanoparticles, and nitrogen-doped carbon electrocatalyst contributes to the excellent electrocatalytic performance of NiFe LDHCNT-Co3O4/NC in the aforementioned reactions. The hydrophilic NiFe LDHs and highly mesoporous carbon matrices provide a favorable ionic pathway for achieving rapid diffusivity and efficient mass transfer while the CNTs and carbon frameworks enhance the electrical conductivity during redox processes 

Tetrafunctional electrocatalyst for oxygen reduction, oxygen evolution, hydrogen evolution, and carbon dioxide reduction reactions

Designing materials with electron/mass transfer effectively improves catalytic activity by synergistic effects between different species. Herein, we report a high-temperature pyrolysis strategy to induce charge transfer of Cu3P loaded TiO2 3D hollow mesoporous carbon nanospheres (Cu3P/TiO2@NC). Density functional theory (DFT) calculations disclose that synergistic between Cu3P and TiO2 can optimize the adsorption of oxygen intermediates and endow fast reaction kinetics. Cu3P/TiO2@NC with hollow mesoporous structure can establish a favorable three-phase interface and shorten the electronic/mass transport path to accelerate reaction kinetics. Consequently, Cu3P/TiO2@NC indicated robust electrocatalytic activity in alkaline medium compared to single-component catalysts and benchmark Pt/C. Cu3P/TiO2@NC exhibits a greater power density of 182.9 mW cm−2 and excellent cyclability over 220 h than Pt/C + RuO2 in Zn-air battery. The flexible properties endow Cu3P/TiO2@NC with promising application prospects in wearable electronic devices. This work may provide an avenue to construct hollow-porous-structured catalysts with synergistic effects for renewable energy devices. 

Synergistic effect and nanostructure engineering of three-dimensionally hollow mesoporous spherical Cu3P/TiO2 in aqueous/flexible Zn–air batteries

The continual rise of the CO2 concentration in the Earth’s atmosphere is the foremost reason for environmental concerns such as global warming, ocean acidification, rising sea levels, and the extinction of various species. The electrochemical CO2 reduction (CO2RR) is a promising green and efficient approach for converting CO2 to high-value-added products such as alcohols, acids, and chemicals. Developing efficient and low-cost electrocatalysts is the main barrier to scaling up CO2RR for large-scale applications. Heteroatom-doped porous carbon-based (HA-PCs) catalysts are deemed as green, efficient, low-cost, and durable electrocatalysts for the CO2RR due to their great physiochemical and catalytic merits (i.e., great surface area, electrical conductivity, rich electrical density, active sites, inferior H2 evolution activity, tailorable structures, and chemical–physical–thermal stability). They are also easily synthesized in a high yield from inexpensive and earth-abundant resources that meet sustainability and large-scale requirements. This review emphasizes the rational synthesis of HA-PCs for the CO2RR rooting from the engineering methods of HA-PCs to the effect of mono, binary, and ternary dopants (i.e., N, S, F, or B) on the CO2RR activity and durability. The effect of CO2 on the environment and human health, in addition to the recent advances in CO2RR fundamental pathways and mechanisms, are also discussed. Finally, the evolving challenges and future perspectives on the development of heteroatom-doped porous carbon-based nanocatalysts for the CO2RR are underlined.

https://www.mdpi.com/2079-4991/12/14/2379/pdf?version=1657621116

R. Kumar

Papers

Quasihexagonal Platinum Nanodendrites Decorated over CoS2‐N‐Doped Reduced Graphene Oxide for Electro‐Oxidation of C1‐, C2‐, and C3‐Type Alcohols

Realizing high thermoelectric performance in p-type RbZn4P3 Zintl compound: a first-principles investigation