Deciphering in-situ surface reconstruction in two-dimensional CdPS3 nanosheets for efficient biomass hydrogenation

Steering on the intrinsic active site of an electrode material is essential for efficient electrochemical biomass upgrading to valuable chemicals with high selectivity. Herein, we show that an in-situ surface reconstruction of a two-dimensional layered CdPS3 nanosheet electrocatalyst, triggered by electrolyte, facilitates efficient 5-hydroxymethylfurfural (HMF) hydrogenation to 2,5-bis(hydroxymethyl)furan (BHMF) under ambient condition. The in-situ Raman spectroscopy and comprehensive post-mortem catalyst characterizations evidence the construction of a surface-bounded CdS layer on CdPS3 to form CdPS3/CdS heterostructure. This electrocatalyst demonstrates promising catalytic activity, achieving a Faradaic efficiency for BHMF reaching 91.3 ± 2.3 % and a yield of 4.96 ± 0.16 mg/h at − 0.7 V versus reversible hydrogen electrode. Density functional theory calculations reveal that the in-situ generated CdPS3/CdS interface plays a pivotal role in optimizing the adsorption of HMF* and H* intermediate, thus facilitating the HMF hydrogenation process. Furthermore, the reconstructed CdPS3/CdS heterostructure cathode, when coupled with MnCo2O4.5 anode, enables simultaneous BHMF and formate synthesis from HMF and glycerol substrates with high efficiency.


Supplementary Note I
All chemicals and reagents used in this work were received and utilized without further purification.The PBS electrolyte used in this study was directly purchased from ThermoFisher Biochemical Products (Beijing) Co., Ltd, and it was stored at room temperature.The pH of PBS in this study was 9.2 + 0.01.
A facile solvothermal method was utilized to synthesize CdS nanoparticles.In detail, commercial powders of thioacetamide (C2H5NS, 0.31g) and cadmium nitrate (Cd(NO3)2, 0.34g) were added to 35 mL isopropanol.The mixture was then sonicated for 10 min, transferred to Teflon-lined stainless steel autoclave, and heated at 150 °C for 12 h to obtain CdS.The resulting product was washed with isopropanol and ethanol, drop-cast on carbon cloth to obtain CdS/CC, and dried overnight in a hot air oven at 60 °C.
The synthesis of MnCo2O4.5 anode is realized via a two-step process.Firstly, the Co(OH)2 precursor was directly synthesized on the nickel foam (NF) substrate through hydrothermal method.Typically, 1.45 g of cobalt nitrate hexahydrate (Co(NO3)2.6H2O),1.5 g urea (CH4N2O), and 0.32 g ammonium fluoride (NH4F) were dissolved in 40 ml of water.The mixture was sonicated for 10 minutes and transferred to the Teflon-lined stainless steel autoclave.A piece of NF substrate (4 x 2 cm 2 ) was immersed in the autoclave and heated at 120 °C for 6 h to grow Co(OH)2 nanowire.Next, Mn was electrochemically deposited on the as-obtained precursor via cathodic deposition process at a constant current of -20mA for 20 min.The plating electrolyte solution contains 0.1M Mn(NO3)2.Finally, the as-obtained electrode was annealed at 400 °C for 3h to yield MnCo2O4.5/NF.The control samples of In2S3 and CdPSe3 nanosheets were synthesized via solvothermal and space confined chemical vapour conversion methods, respectively.The synthesis protocol for CdPSe3 is almost the same to CdPS3.For the growth of CdPSe3, a powder mixture containing P and Se (1:4, 0.75g) was placed in the front zone, and the as-prepared CdS/CC precursor was kept at the back zone.After pumping the tube with Ar gas for several minutes, the front and back zones were simultaneously heated to 300 and 450 °C, respectively, within 20 min under 100 sccm Ar gas flow.
The reaction lasted 60 min, and the final temperature of the front and back zone was 330 and 450 °C, respectively.
the synthesis of CdPS3 nanosheets on carbon cloth substrate.a, Schematic configuration of the CVD tubes.The custom-designed silica socket tube was used, and the CdS precursor and mixture of P and S were kept at two different ends of the tube.b, the temperature profile for the synthesis of CdPS3.Supplementary Fig. 4| a-b, SEM images of as-synthesized CdPS3 NS on CC. c, the corresponding EDX mapping.Supplementary Fig. 5| Full XPS spectrum of as-synthesized CdPS3 nanosheet 10| a, The NMR signals of HMF with different concentration b, the corresponding calibration curve.Supplementary Fig. 11| The SEM image (a-c) and corresponding EDX elemental analysis (d) of clean carbon cloth substrate.Supplementary Fig. 12| Electrocatalytic performance of carbon cloth substrate toward HMF hydrogenation.The performance of clean carbon cloth substrate was evaluated in 0.1 M PBS (pH = 9.2) electrolyte using 10 mM HMF as the initial substrate concentration.Supplementary Fig. 13| Nyquist plot for CdPS3 electrode in a, 0.1 M PBS (pH = 9.2) b, 10 mM HMF. c, the corresponding charge transfer resistance (Rct) in a and b after fitting.
The NMR signal of 10 mM HMF in 0.1 M PBS electrolyte before and after electrolysis at -0.7 VRHE.Supplementary Fig. 15| The digital image of electrochemical cell (a) and setup (b) used for in situ Raman spectroscopy analysis.
Morphology characterizations and electrocatalytic activity of In2S3 nanosheet catalyst for hydrogenation of HMF to BHMF.a-b, SEM images of In2S3 nanosheets grown on carbon cloth substrate.c, LSV curves (without iR correction) of In2S3 nanosheet electrode in 0.1 M PBS (pH= 9.2) electrolyte with and without 20 mM HMF. d, Comparison of HMF hydrogenation activity of In2S3 nanosheet electrodes activated in 0.1 M PBS in the absence of HMF and under 10 and 25 CV activation cycles in the presence of HMF (shaded in light yellow).