Enriching Reaction Intermediates in Multishell Structured Copper Catalysts for Boosted Propanol Electrosynthesis from Carbon Monoxide.

Fine-tuned catalysts that alter the diffusion kinetics of reaction intermediates is of great importance for achieving high-performance multicarbon (C2+) product generation in carbon monoxide (CO) reduction. Herein, we conduct a structural design based on Cu2O nanoparticles and present an effective strategy for enhancing propanol electrosynthesis from CO. The electrochemical characterization, operando Raman monitoring, and finite-element method simulations reveal that the multishell structured catalyst can realize the enrichment of C1 and C2 intermediates by nanoconfinement space, leading to the possibility of further coupling. Consequently, the multishell copper catalyst realizes a high Faraday efficiency of 22.22 ± 0.38% toward propanol at the current density of 50 mA cm-2.

Enriching the Local Concentration of CO Intermediates on Cu Cavities for the Electrocatalytic Reduction of CO2 to C2+ Products.

The electrochemical carbon-dioxide reduction reaction (CO2RR) to high-value multi-carbon (C2+) chemicals provides a hopeful approach to store renewable energy and close the carbon cycle. Although copper-based catalysts with a porous architecture are considered potential electrocatalysts for CO2 reduction to C2+ chemicals, challenges remain in achieving high selectivity and partial current density simultaneously for practical application. Here, the porous Cu catalysts with a cavity structure by in situ electrochemical-reducing Cu2O cavities are developed for high-performance conversion of CO2 to C2+ fuels. The as-described catalysts exhibit a high C2+ Faradaic efficiency and partial current density of 75.6 ± 1.8% and 605 ± 14 mA cm-2, respectively, at a low applied potential (-0.59 V vs RHE) in a microfluidic flow cell. Furthermore, in situ Raman tests and finite element simulation indicated that the cavity structure can enrich the local concentration of CO intermediates, thus promoting the C-C coupling process. More importantly, the C-C coupling should be major through the *CO-*CHO pathway as demonstrated by the electrochemical Raman spectra and density functional theory calculations. This work can provide ideas and insights into designing high-performance electrocatalysts for producing C2+ compounds and highlight the important effect of in situ characterization for uncovering the reaction mechanism.

Hierarchical S-modified Cu porous nanoflakes for efficient CO2 electroreduction to formate.

Electrochemical reduction of CO2 into liquid fuels is a promising approach to achieving a carbon-neutral energy cycle but remains a great challenge due to the lack of efficient catalysts. Here, the hierarchical architectures assembled by ultrathin and porous S-modified Cu nanoflakes (Cu-S NFs) are designed and constructed as an efficient electrocatalyst for CO2 conversion to formate with high partial current density. Specifically, when integrated into a gas diffusion electrode in a flow cell, Cu-S NFs are capable of delivering the ultrahigh formate current density up to 404.1 mA cm-2 with a selectivity of 89.8%. Electrochemical tests and theoretical calculations indicate that the superior performance of the designed catalysts may be attributed to the unique structure, which can provide abundant active sites, fast charge transfer, and highly active edge sites.

In situ formed N-containing copper nanoparticles: a high-performance catalyst toward carbon monoxide electroreduction to multicarbon products with high faradaic efficiency and current density.

Developing efficient catalysts for electrochemical carbon monoxide reduction (ECOR) with high faradaic efficiency (FE) and current density is highly desirable. In this work, we demonstrate that the N-containing Cu nanoparticles formed in situ by the reconstruction of cuprous 7,7,8,8-tetracyanoquinodimethane possess high-performance ECOR ability. Impressively, the N-containing Cu nanoparticle catalyst presented the highest FE of 81.31% towards multicarbon products with a high commercial-grade partial current density of 162.62 mA cm-2, which is among the best of the reported Cu-based ECOR catalysts at -0.69 V versus the reversible hydrogen electrode. The retained ligand on the formed catalyst via the convenient in situ formation is crucial for the selectivity of multicarbon products. This work will arouse enthusiasm for the utilization of reconstruction features for designing ligand-containing catalysts with enhanced artificial carbon fixation ability.

Fight for carbon neutrality with state-of-the-art negative carbon emission technologies.

After the Industrial Revolution, the ever-increasing atmospheric CO2 concentration has resulted in significant problems for human beings. Nearly all countries in the world are actively taking measures to fight for carbon neutrality. In recent years, negative carbon emission technologies have attracted much attention due to their ability to reduce or recycle excess CO2 in the atmosphere. This review summarizes the state-of-the-art negative carbon emission technologies, from the artificial enhancement of natural carbon sink technology to the physical, chemical, or biological methods for carbon capture, as well as CO2 utilization and conversion. Finally, we expound on the challenges and outlook for improving negative carbon emission technology to accelerate the pace of achieving carbon neutrality.

A supersensitive biosensor based on MoS2 nanosheet arrays for the real-time detection of H2O2 secreted from living cells.

The fast and accurate real-time monitoring of hydrogen peroxide (H2O2) secreted from living cells plays a critical role in clinical diagnosis and management. Herein, we report low-cost and self-supported MoS2 nanosheet arrays for non-enzymatic eletrochemical H2O2 detection. Under the optimal test conditions, such MoS2 electrodes exhibit extremely promising electrocatalytic performance with a low detection limit of 1.0 µM (S/N = 3) and an excellent sensitivity of 5.3 mA mM-1 cm-2. Furthermore, the detection of the trace amount of H2O2 secreted from live A549 cancer cells was successfully performed with this biosensor.

A novel FeS-NiS hybrid nanoarray: an efficient and durable electrocatalyst for alkaline water oxidation.

It is highly important to develop cost-efficient electrocatalysts for the oxygen evolution reaction (OER). In this communication, we report a novel FeS-NiS hybrid nanosheet array on Ti mesh as a highly efficient non-noble-metal electrocatalyst for OER. This catalyst requires an overpotential of 260 mV to afford a current density of 10 mA cm-2 in 1.0 M KOH, 100 and 110 mV less than those required for FeS and NiS, respectively. In addition, this catalyst shows good durability, with maintenance of its catalytic activity for at least 25 h.

Dual signal amplification photoelectrochemical biosensor for highly sensitive human epidermal growth factor receptor-2 detection.

Photoelectrochemical (PEC) biosensor for highly sensitive detection of breast cancer biomarker human epidermal growth factor receptor-2 (HER2) is reported utilizing a dual signal amplification strategy. The biosensor was prepared based on tungsten sulfide nanowire array on Ti mesh (WS2 NW/TM). Such WS2 NW/TM electrode can generate photoelectric signal under visible light excitation. The HER2 aptamer was wrapped onto the nanowire array surface for specific binding with HER2 molecules, and gold nanoparticles (Au NPs) that modified with glucose oxidase (GOx) and HER2 binding peptide was utilized for signal amplification. The H2O2 that generated by GOx catalyzed glucose reaction and localized surface plasmon resonance of Au NPs can both enhance the PEC current intensity of the biosensor, leading to dual signal amplification. The PEC current intensity is enhanced linearly with HER2 concentration in the 0.5-10 ng/mL range with limit of detection of 0.36 ng/mL. Such biosensor was applied for the detection of HER2 in breast cancer serum samples with detection results in good agreement with commercial ELISA results.

Enhanced electrocatalytic activity of water oxidation in an alkaline medium via Fe doping in CoS2 nanosheets.

The development of new electrocatalysts is critical for efficient water electrolysis to produce hydrogen. In this communication, we report a novel electrocatalyst for the oxygen evolution reaction (OER) which is realized via Fe doping in CoS2 nanosheets (Fe-CoS2). This catalyst shows an overpotential of 302 mV for a current density of 10 mA cm-2, 85 mV less than that for CoS2. In addition, Fe-CoS2 also exhibits high catalytic stability.

Recent progress in transition metal phosphides with enhanced electrocatalysis for hydrogen evolution.

Increasing demand for hydrogen energy has boosted the exploration of inexpensive and effective catalysts. Transition metal phosphides (TMPs) have been proven as excellent catalysts for the hydrogen evolution reaction (HER). Very recently, the search for TMP-based catalysts has being mainly directed at enhanced electrocatalytic performance. Hence, a concluded guideline for enhancing HER activity is highly desired. In this mini review, we briefly summarize the most recent and instructive developments in the design of TMP-based catalysts with enhanced electrocatalysis for hydrogen evolution from composition and structure engineering strategies. These strategies and perspectives are also meaningful for designing other inexpensive and high-performance catalysts.

Cr2O3 nanofiber: a high-performance electrocatalyst toward artificial N2 fixation to NH3 under ambient conditions.

NH3 synthesis heavily depends on the energy-intensive Haber-Bosch process, which produces serious carbon emission. Electrocatalytic N2 reduction emerges as an environmentally benign process for sustainable artificial N2 fixation but requires efficient, stable and selective catalysts for the N2 reduction reaction (NRR). Here, we report that Cr2O3 nanofiber behaves as a superb non-noble-metal NRR electrocatalyst for artificial N2 fixation to NH3, with excellent selectivity under ambient conditions. In 0.1 M HCl, this catalyst achieves a high Faradaic efficiency of 8.56% and a high NH3 formation rate of 28.13 µg h-1 mgcat.-1, placing it amongst the most active aqueous-based NRR electrocatalysts. Moreover, this catalyst also shows strong electrochemical durability during electrolysis and the recycling test. It opens a new avenue to explore the rational design of Cr-based nanostructures as advanced catalysts for N2 fixation and other applications.

Enhanced electrocatalysis for alkaline hydrogen evolution by Mn doping in a Ni3S2 nanosheet array.

Developing earth-abundant and efficient catalysts for the hydrogen evolution reaction (HER) is highly desirable. In this communication, we report the development of a Mn-doped Ni3S2 nanosheet array on Ni foam (Mn-Ni3S2/NF) as a superior and durable catalyst for alkaline hydrogen evolution. Such Mn-Ni3S2/NF demands an overpotential of 152 mV to afford 10 mA cm-2 in 1.0 M KOH, 46 mV less than that for Ni3S2/NF. Furthermore, this catalyst also shows high long-term electrochemical durability. This work provides important guidance for exploring optimal HER catalysts.

Highly efficient electrochemical ammonia synthesis via nitrogen reduction reactions on a VN nanowire array under ambient conditions.

The development of a sustainable route to ammonia production is one of the most attractive targets in chemistry. The primary method of ammonia production, Haber-Bosch process, can bring about excessive consumption of fossil fuels and large CO2 emission. In this communication, we develop a VN nanowire array on carbon cloth (VN/CC) as a high-performance catalyst for the nitrogen reduction reaction (NRR) under ambient conditions. Such an electrocatalyst achieves high ammonia yield (2.48 × 10-10 mol-1 s-1 cm-2) and faradaic efficiency (3.58%) at -0.3 V versus RHE in 0.1 M HCl, outperforming most reported results for N2 fixation under ambient conditions, and even comparing favorably with those obtained under high temperatures and/or pressures. This work not only provides us an attractive catalyst material for the NRR in acidic media, but would also open up an exciting new avenue to the rational design and fabrication of transition metal nitrides for the NRR.

Al-Doped Ni2P nanosheet array: a superior and durable electrocatalyst for alkaline hydrogen evolution.

It is highly desired to develop high-efficiency and low-cost catalysts for the hydrogen evolution reaction (HER). Herein, we report the development of an Al-doped Ni2P nanosheet array on Ti mesh as a high-performance and durable electrocatalyst for the HER in 1.0 M KOH. Such a catalyst demands an overpotential of 129 mV to afford 10 mA cm-2 and maintains its catalytic activity for at least 20 h. This work offers us a promising cost-effective catalyst for large-scale electrolytic production of hydrogen fuels.

Interface engineering of a CeO2-Cu3P nanoarray for efficient alkaline hydrogen evolution.

It is of great importance to design and develop highly active electrocatalysts for the hydrogen evolution reaction (HER) under alkaline conditions. In this work, we report the development of a CeO2-Cu3P nanoarray supported on nickel foam (CeO2-Cu3P/NF) as an excellent HER catalyst with the demand of an overpotential of only 148 mV to deliver a geometrical catalytic current density of 20 mA cm-2 in 1.0 M KOH. Remarkably, this catalyst also shows strong long-term electrochemical durability for at least 100 h with nearly 100% Faradaic efficiency. Density functional theory calculations reveal that the CeO2-Cu3P/NF hybrid has a lower water dissociation energy and a more thermo-neutral hydrogen adsorption free energy.

A Cu3P-CoP hybrid nanowire array: a superior electrocatalyst for acidic hydrogen evolution reactions.

It is highly attractive to construct cost-effective hybrid electrocatalysts with superior activity for the hydrogen evolution reaction (HER) in acids. In this communication, we report a novel structure consisting of a Cu3P-CoP hybrid nanowire array supported on carbon cloth (Cu3P-CoP/CC) as a superior HER electrocatalyst in acidic media. Owing to the synergistic effect between Cu3P and CoP, this Cu3P-CoP/CC catalyst exhibits superior catalytic HER performance, needing an overpotential of 59 mV to drive a current density of 10 mA cm-2 in 0.5 M H2SO4, 24 and 130 mV less than that for CoP/CC and Cu3P/CC, respectively. Moreover, this catalyst also shows high long-term electrochemical durability.